I have a 1999 Fleetwood American Eagle with a Cummins ISC 8.3 L motor that is very difficult to start lately. The problem has now worsened to the point where I can't start it all. When it was starting, it would often idle for 30 seconds to 2 minutes and then stall out. But once I re-started it again a more few times, it would eventually stay running and run like a champ. It was often very easy to start the same day and even usually the next day but if it sat a few days, the same difficult starting process start over again.
Here is what I have troubleshooted thus far. I removed the lift pump and it seems to be working just fine. I know this b/c when I submerge the inlet in fuel and connect power to the motor, it pumps fuel out of the outlet quite vigorously. So I reinstalled the lift pump and hooked everything back up except the outlet hose. I turned the key to the on position to trigger the pump to prime but nothing comes out. It did this at least five times. Why won't it draw fuel when I hook everything back up? Shouldn't fuel spray from the outlet when no hose is connected? Something seems amiss there.
So then I re-connected the outlet hose of the lift pump which first goes to a fuel filter. I removed this filter, filled it with fuel, and reconnected. After cranking the motor for 20 seconds or so, it started but only ran for about 30 seconds before stalling. I crank it again but it won't start at all. So I pulled the fuel filter out again and it was about half full. I filled it to the top again with fuel, re-connected, and the motor starts but again only runs for about 30 seconds. I did this a third time, same result. I idled the RPM quite high the last time thinking this may help but no success.
From what I can tell, the lift pump is not priming the filter. The lift pump motor is buzzing so I know it's working. But once it starts, I thought the motor no longer relies on the lift pump to pull fuel.
I've read similar posts stating there could be a hole in the fuel line from the tank to the lift pump. How would I figure this out? My fuel tank is about 1/4 full. I read about pressuring the fuel tank to allow the lift pump to draw.
Not sure what to do from here. Thanks for any help.
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The ISC lift pump is just a primer pump for the CAPS fuel system , and runs for only 30 sec after start up ; others have stated that the lift pump needs to see the starter bumped to start the cycle .
The lift pump gasket between the top of the pump and the fuel manifold is prone to leaking ; both fuel out and air in ; and there is an updated gasket available .
I'll see if any of the info on CAPS has info on the mechanical lift pump portion testing.
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99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
Are you sure the fuel gauge is accurate?
I'd dump in ten gallons of diesel and see what happens.
Yes, your lift pump only runs appx 45 seconds when the key is turned to the run position. It is simply a priming pump for the caps injector pump.
If your sure you have fuel I'd suspect a bad fuel line, possibly collapsed internally, or a possible restriction/debris in the tank.
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2000 Alpine 36 FDS #74058
"Go fast enough to get there, but slow enough to see”
Location: Over the next hill, around the next curve...
Posts: 5,714
If I read that right - 1st post? If so - WELCOME TO IRV2!!!
Since it starts and runs for a minute or two before stopping, that indicates that at least at first - the Lift Pump is 'Lifting' the fuel to the CAPS to feed it into the pistons. (Concur with the Lift Pumps are a 30 seconds or so 'At Start-up' pump, then turn off.)
As mentioned, Lift Pumps can have leaks around the gaskets where they connect the pump to the block. (A visual inspection of the passenger side of the engine (Google diagrams of your era's engines, and they should point to the Lift Pump.), would show evidence of fuel leakage if that was a problem.) A leaking gasket, can allow 'air' into the fuel flow the CAPS systems. Which could cause an engine to starve for fuel once the Lift Pump motor stops running.
Other things to consider"
-Fuel Filter's - How old are they? Could they have been contaminated? (If you do not see signs of Leakage at the Lift Pump - this would be my first suspect.)
-Inline Fuel Filters (Some manufactures add an Inline Fuel Filter on the line between the Fuel Tank and the engines Primary (And if appropriate, Secondary.) Fuel Filters. (I've know of many who were not aware one was on their chassis, and years later they clog enough to cause a fuel flow/starvation problem.)
-Lift Pumps do usually have an internal screen like filter, that has been known on some applications (Usually coaches with only one Fuel Filter. And our coach probably has two. Where contaminants and or gelling will partially clog the screen.)
-Error codes? If you can borrow a reader, look to see if the Engine ECM has a recorded Error Code related to fuel delivery.
Those are the ones that would be the most likely... But others exist too.. So if none of those pan out, let us know, and we'll all do our best to help.
Welcome again, and hope this turns out to be an easy one to solve!!!
Smitty
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Pausing 4 Family Opportunities - We'll be back! 04 Country Coach Allure followed by 07 Magna OnDRoad for The JRNY! Enjoy life...
I found a source and bought a spare fuel lift pump gasket to carry as an emergency spare. I bought it from
Capital Volvo
Montgomery AL
Part #4928511
Price ~$8
Initially when I bought my rig I followed the instructions for changing the fuel filters, at the time it said not to prefill the filter. Back about 6 years ago I did this and could not get the rig to start so I pulled the filters and the rig started right up. Now I think the instructions on the filters call for them to be prefilled so that's what I do and haven't had an issue since.
Check fuel level in tank.
I had read one instance where the fuel hose going to the primary filter had actually disintegrated and blocked the fuel from getting to the filter, you may pull that hose and check if you get fuel out of it and look for blockage.
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Jim J
2002 Monaco Windsor 38 PKD Cummins ISC 350 8.3L
2005 Jeep Grand Cherokee w/5.7 Hemi
From the info I have on the CAPS fuel system, the " gear pump " that's the portion of the CAPS injection pump that pulls fuel from the tank after start up and the electric lift pump turns off .
Testing of the gear pump takes special fittings and a fuel pressure gauge and the specs are as follows.
Pressure @ 150 cranking RPM ; 10 psi , 5 psi is an absolute minimum.
The pdf I have on CAPS is three times the posting limit of the forums , it does contain other information , that I have no idea how to eliminate.
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99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
I think you have a restriction stopping fuel getting to the lift pump. Run a line from the lift pump intake to a bucket of fuel. I think it will run OK then.
First of all, thank you very much for the input so far everybody.
Here's the latest.
I bought a 6 foot hose to connect the lift pump directly to a bucket of diesel fuel to bypass potential problems from the fuel tank to the lift pump. I disconnected the outlet of the lift pump just to verify it would draw fuel when key is turned on and sure enough it does. So I reconnected the outlet to lift pump. By the way, I replaced both fuel filters before doing this, the one immediately after the lift pump and the other in line filter which is bypassed anyways with my bucket of fuel set-up.
After verifying fuel is pumping out of the lift pump, I turned the key on to make sure fuel was filling the new filter. I didn't try to start it, just primed the system by turning the key on a few times. I then removed the filter to make sure it was full of full but it WAS COMPLETELY EMPTY! How is this possible I thought. So I removed the filter and turned the key on to make sure fuel was flowing out of the filter mount apparatus, and sure enough it was. So this ruled out any blockage in the short run b/t the lift pump and the filter. So I reconnected the empty filter and engaged the primer pump again a few times without cranking the motor. I removed the filter to see if it filled up and there's not a drop of diesel in the filter. How it is possible that fuel dumps out of the filter mount when no filter is attached but when I connect the filter, there's absolutely no trace of fuel? By screwing on the filter, is there some type of valve that being triggered to block flow into the filter. Is it b/c I'm loading an empty filter and the air won't allow fuel to go in but that can't be the reason, could it? It's a complete head scratcher to me.
So I then removed the filter, filled it to the top with fuel, screwed it back on, crank the motor, and it starts after about 30 seconds of cranking. But it runs for 30 seconds and the motor dies just like I explained in my first post. I pulled the filter off after the motor stopped and it's about 1/2 full.
I called Cummins today and explained the problem but they had no explanation why the fuel filter would not fill. They did suggest routing the return line that normally goes back to the fuel tank into the same bucket but not sure why that would help but I'll try anything. They said they error codes would be very helpful I don't have that ability. Are these code readers common enough that I could borrow one?
Someone suggested bleeding possible air in the fuel line by loosing the fuel lines into the injectors.
What the heck is going on? Maybe the gear pump is not drawing fuel as it should be once it starts? Then I may have a bigger problem. But I would REALLY like to know why the fuel filter is empty when I know fuel is following to and out of the filter housing.
To address some of the comments:
I don't have the tools to test the gear pump pressure.
Fuel tank level is fairly low but I bypassed it with my set-up.
Do not see any signs of leakage.
Lift pump screen is clean. Lift pump gasket appears normal.
First of all, thank you very much for the input so far everybody.
Here's the latest.
I bought a 6 foot hose to connect the lift pump directly to a bucket of diesel fuel to bypass potential problems from the fuel tank to the lift pump. I disconnected the outlet of the lift pump just to verify it would draw fuel when key is turned on and sure enough it does. So I reconnected the outlet to lift pump. By the way, I replaced both fuel filters before doing this, the one immediately after the lift pump and the other in line filter which is bypassed anyways with my bucket of fuel set-up.
After verifying fuel is pumping out of the lift pump, I turned the key on to make sure fuel was filling the new filter. I didn't try to start it, just primed the system by turning the key on a few times. I then removed the filter to make sure it was full of full but it WAS COMPLETELY EMPTY! How is this possible I thought. So I removed the filter and turned the key on to make sure fuel was flowing out of the filter mount apparatus, and sure enough it was. So this ruled out any blockage in the short run b/t the lift pump and the filter. So I reconnected the empty filter and engaged the primer pump again a few times without cranking the motor. I removed the filter to see if it filled up and there's not a drop of diesel in the filter. How it is possible that fuel dumps out of the filter mount when no filter is attached but when I connect the filter, there's absolutely no trace of fuel? By screwing on the filter, is there some type of valve that being triggered to block flow into the filter. Is it b/c I'm loading an empty filter and the air won't allow fuel to go in but that can't be the reason, could it? It's a complete head scratcher to me.
So I then removed the filter, filled it to the top with fuel, screwed it back on, crank the motor, and it starts after about 30 seconds of cranking. But it runs for 30 seconds and the motor dies just like I explained in my first post. I pulled the filter off after the motor stopped and it's about 1/2 full.
I called Cummins today and explained the problem but they had no explanation why the fuel filter would not fill. They did suggest routing the return line that normally goes back to the fuel tank into the same bucket but not sure why that would help but I'll try anything. They said they error codes would be very helpful I don't have that ability. Are these code readers common enough that I could borrow one?
Someone suggested bleeding possible air in the fuel line by loosing the fuel lines into the injectors.
What the heck is going on? Maybe the gear pump is not drawing fuel as it should be once it starts? Then I may have a bigger problem. But I would REALLY like to know why the fuel filter is empty when I know fuel is following to and out of the filter housing.
To address some of the comments:
I don't have the tools to test the gear pump pressure.
Fuel tank level is fairly low but I bypassed it with my set-up.
Do not see any signs of leakage.
Lift pump screen is clean. Lift pump gasket appears normal.
Sounds like lift pump is no good. It will pump fuel when you have it disconnected and zero restriction. As soon as you hook it up it cannot even overcome the air in the filter.
That would also explain why once it's running and purged all the air from the system it would run fine until it sits a while again.
Most likely the reason Cummins told you to route the return line into the bucket would be because there is a check valve in the lift pump and if something is wrong in that area, it "could" return the fuel to the tank as a lesser restriction than priming the filter. By putting the line in the bucket the fuel may pump correctly. See if you know anyone that has a cheap electric fuel pump and hook it up from the bucket directly to the filter and I bet everything works correctly.
The only bad part is I'm not confident enough to tell you definitely go buy a lift pump....but, it's my bet. Good Luck !
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1999 American Dream 40DVS
Spartan Chassis, Cummins ISC 330
Hint: Add a fuel pressure gauge on top of your fuel filter block
I'm going to assume you have a CAPS system like my 2004 Itasca Horizon 40AD. That said, maybe this will help you with your engine problems:
* Lift pump runs and pumps for 30 seconds and turns off. All good there.
* But Engine stalls after the prime is lost.
* This implies your CAPS low pressure gear
pump cannot maintain -4PSI or -5PSI of
vacuum pressure (suction).
==> Are you are sure your 3-lift pump manifold bolts are tight?
* If you engine dies then the CAPS pump is starved of fuel.
*Maybe due to 1/4 tank problem. How much fuel is in your tank? (If it starts you have air getting sucked into the lines somewhere.) Be sure to check your fuel line fittings too!
*Fuel tank vent may be clogged. Try removing
your fuel tank cap -- and then restart
* HOW COLD IS IT OUT SIDE? Below 40F? Maybe your grid heater is not working right?
MOVING TO LEVEL II
Maybe your CAPS low pressure gear pump sheared off its drive link so it's not able to pump fuel... probably not... but it has been known to happen.
More likely, you have a fuel delivery problem or a fuel restriction problem.
The delivery side is about finding air leaks in the fuel line vs. the restriction problem which implies a clog in the fuel line... including the fuel return line.
That check-valve in the Lift Pump has been known to cause a problem, but if your engine starts this is probably not your problem.
* Algae is also a problem. Do you have any signs of green flakes in your fuel bowl? ...The black flakes are usually dead algae. If you do then try priming your fuel filter with Seafoam and start to flush through your CAPS pump. (Don't be alarmed by the smoke... it will go away after the Seafoam burns thru and the un-burned Seafoam is returned to your fuel tank.)
There is also a small screen filter in the low pressure gear pump about 1" tall. This can trap algae too, but algae typically invades your Accumulator. (That block looking thing on top of the pump.)
HINT: A CHEAP WAY TO MEASURE YOUR FUEL PRESSURE
* Do you have 1 or 2 filters?
Check the top of your filter block. Do you have a 10mm port on top?
If you have a port on top of your fuel filter block, then you can easily install a fuel pressure gauge to monitor your fuel pressure. Of course, you will not be able to read it when you are traveling on the road, unless someone is looking at your engine from inside your bedroom engine access, but for less than $20 you can at least monitor your fuel pressures when you are parked.
I recommend everyone add one of these LIQUID FILLED fuel gauges, so in times like this you have some basic information to help you know where to look. Just be sure to order the right adapter. The thread to the filter block is 10mm x 1.0; but your gauge thread can either be 1/8" NPT or 1/4" NPT (aka pipe).
Note: Pipe threads have a taper so you can use Teflon tape to seat, but that 10mm thread is not tapered so you need a neoprene rubber washer you can get at your local ACE Hardware store. (And do not buy the regular rubber washer made for water faucets!)
Note: Some gauges point up while others are read from the side.
1-1/2" Oil Filled Pressure Gauge, Stainless Steel Case, Brass, WOG, 1/8" NPT, Center Back Mount, 30HG/30PSI
So if all the above checks out, then you probably need to decide where to spend your repair dollars on a fishing expedition:
A) You can break down your CAPS pump and replace the low pressure gear pump.
B) You can clean the accumulator if you think you have an algae problem.
Note: If you suspect an algae problem, have you tried priming your fuel filter with Seafoam and then starting your engine? I would do this before tearing into the CAPS pump.
C) You can upgrade to a FASS-TS or AirDog-4G electric fuel pump.
And if you want to learn more about upgrading your fuel system, which I highly recommend, then you might look at the FASS-TS or AirDog-4G electric pump (aka lift pump upgrade) by clicking on this link:
Note: If it turns out you still have a problem after adding the FASS, it's not money down the drain. In fact, you will be glad you did for reasons you can read about in the other threads on this subject.
...then you probably need to replace your Low Pressure Gear pump in the CAPS pump; but if you don't see a problem with the drive shaft after you take the pump apart, then I would recommend you buy a CAPS pump rebuild.
What I would not do is spend money to replace a stock lift pump, because that money would be better spent upgrading to a FASS or AirDog lift pump instead... and then you can decide on bypassing the stock fuel pump manifold or not.
You said you verified the lift pump was working with a hose in the bucket.
I would try this. Have all the fuel lines connected except the intake to the lift pump. Like you did before, draw fuel out of the bucket by cycling the lift pump. Loosen the secondary filter just enough to let air escape. Do you see fuel and air escaping from the filter? Let all the air escape. Now check to see if the filter is full. If it’s full of fuel, I would guess air being pulled in due to bad hose, bad connections or bad gasket from tank to lift pump. I would also check for fuel pressure on the top port of the secondary filter. Also, those inline filters are junk.
Imnprsd has a great write up for upgrading your fuel system before you damage your CAPS pump.
Bill
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2003 Country Coach Intrigue 36'
Cummins ISL 400
You said you verified the lift pump was working with a hose in the bucket.
I would try this. Have all the fuel lines connected except the intake to the lift pump. Like you did before, draw fuel out of the bucket by cycling the lift pump. Loosen the secondary filter just enough to let air escape. Do you see fuel and air escaping from the filter? Let all the air escape. Now check to see if the filter is full. If it’s full of fuel, I would guess air being pulled in due to bad hose, bad connections or bad gasket from tank to lift pump. I would also check for fuel pressure on the top port of the secondary filter. Also, those inline filters are junk.
Imnprsd has a great write up for upgrading your fuel system before you damage your CAPS pump.
Well folks, I'm pretty certain it's my lift pump. One of three bolts securing the lift pump motor to the fuel manifold is stripped. I can literally turn it with my hand the entire way down. The other two are tight though. The motor runs fine when I connect the lift pump intake and return line to a bucket of fuel 5 feet way. But when I reconnect to the normal fuel tank lines, I can't keep the motor running. Furthermore, I am now noticing diesel fuel leaking from the lift pump. I can't tell where exactly but that can't be good. I am hoping the stripped bolt housing along with maybe a worn out gasket is allowing air to enter the system and fuel to leak out. Would this explain why it works with a very short run of hose to my buckets but not when reconnected to normal fuel lines. As in the pump needs to work much harder to accomplish the latter? I think all the repeated cycling of the lift motor has also taken its toll. I am starting to notice more inconsistent sounds from the lift pump motor, like it's really laboring. For a moment yesterday, I thought my coach batteries had low charge b/c the lift pump sounded like it was firing at half speed. Bottom line, I think I have enough evidence to go with a new lift pump. Any advice on where to get it? Should I pay top dollar and buy from Cummins or go after market? I know some have recommended the FASS system but that's more than I would like to invest and a little over my head. Just want this thing running so we can take our two or three annual trips. Thanks so much for all your help and suggestions. I don't have it fixed yet but I am optimistic.
About a $700 diy upgrade and eliminates the oem lift pump by simply adding a relay and one AN10 male/male fitting to bypass the bad pump.
You will still retain the oem lift pump and utilize the return manifold portion of it. It shouldn't leak this way.
The FASS will give you 17psi positive fuel pressure to your CAPS pump ALWAYS and polish your fuel thru two additional filters (one water sep) at 100 gph. It's how it should have been built in the first place.....
or you could spend slightly less on an OEM replacement lift pump and risk another breakdown or lunching the CAPS pump. That's the $6000 question, with a pretty easy answer IMHO.
Take the time to read all of Imnprsd (and others) posts to decide for yourself. I'd rather spend a couple days upgrading than broke down in Podunk Indiana looking at a huge bill and grumpy wife any day.
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2000 Alpine 36 FDS #74058
"Go fast enough to get there, but slow enough to see”
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