iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!
You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!
I would double check your fuel line. There is definitely supposed to be a second fuel filter. And I would recommend testing some of that new fuel you put in. Since you would have to empty the tank to drop it and get at the fuel pump; put the fuel in another vehicle. You may have gotten some bad gas. Especially since you can't get gen to start. BTW, gen has its own fuel pump and siphones from a separate line. That's why if your tank drops below 1/2-1/3, the gen won't run. As for dropping the tank, OUCH! You may need a jack just for the tank. The tank on my '87 Pace Arrow is heavy gauge steel and 60 gallon size. That's a lot of weight to try and manhandle with one hand when those hold down straps start coming loose; especially while laying in your back.
On my 93' I'm only aware of one fuel filter.
X2 on generator having its own fuel delivery/pump.
The first time I read this I thought that it could be the fuel pressure relief switch/sensor. I also thought it could be the one sensor I didn't see you had changed yet, the throttle position sensor. In all reality though I have to think the timing of your problem, after you had added 40 gallons of gasoline, is odd.
Too much water in the gas?
Too much ethanol in the gas?
Filter at the stations fuel pump not working?
On a throttle body fuel injection system I think your less likely to have pump problems. JMO. The Vortec series that replaced them run at much higher pressures and are particular about not starting if the pump is short a pound or two in pressure at startup. That isn't to say your pump isn't bad though, It just wouldn't be my 1st guess.
Good luck on the full-time move. I wonder if you have an OBD1 port?
I have definitely only been able to find one filter, the fuel line from the filter all the way up to the front is solid, and may also be all the way up to the throttle body.
I don't think it's bad gas as we filled our car the same day at the same station after working on the rig. Also don't think its bad fuel because the generator ran just fine for a while as well.
How common is it for timing to slip after just running at idle to recharge the batteries?
I also am not thinking it's the pump as I hear it start whirring after turning the key, and I am definitely getting fuel to the engine. How common is it for the fuel pump to be dying out slowly? In my experience with fuel pumps, they are either working or not at all.
We do have an OBD1, and I only get code 12 nothing else.
Also, the engine sounds pretty good if i feather the gas and get it up to an rpm that it likes. Would that be indicative of timing being off?
If it was carburetor fed, I would say check your choke settings. And some of the early throttle body injection systems used both a tank electrical pump and the oldstyle engine operated pump in series. Does your fuel line come into the engine compartment behind the motor, or does it run up to the front of the motor? If it is one of the early double pump type, the engine pump may be going out and it's starving for gas until the rpms get the secondary pump working faster. Just a thought. And since your motorhome may have been completed in '90; you may have an older chassis under it. Mine says '87 but the chassis/engine is '85.
AT Slm32123: You mentioned in a previous post that you suspected the rented fuel pressure gauge was faulty. Have you since been able to confirm the actual fuel pressure reading?
I know its a pain to do on a TBI engine, because you need that Actron adapter. https://www.summitracing.com/parts/a...hoCRJ4QAvD_BwE
I would not rule out "Old Gas". Notice I did not say bad gas.
Why?
When we picked up our 96 TBI 454 the gas was years old. It had been stored with Sta-Bil fuel additive. But you can ask only so much from a product that is intended for winterizing lawn and seasonal use gas powered equipment. You are still going to loose octane rating over months. Good explanation by Sunoco https://www.sunocoracefuels.com/tech...w-octane-fuels
Our RV engine started up okay after spraying with Ether, and drove some 120 miles under light throttle just fine. If we gave it any higher rpm or wider throttle opening (load) demands, she would cough and spit.
First fresh 30 gallons of fuel,....
The engine started easier and easier, however the cough and sputter continued to persist for another 6-8 weeks. During that time we adding 20 gallons of fresh fuel 3-5 more times. Seems it takes a long time to wash out an 80 gallon tank, and subsequently burn all of that 80 gallons of gasoline residue away. Every few weeks we added another 20-30 gallons of fuel, while we were repairing things on the RV, but we were still just diluting the old gas with fresh gasoline.
Not long after we went on a 2500 mile trip through the Southwest and poured hundreds of gallons through the RV. Never completely noticed when the cough under hard throttle went away, but it did. It has been two years and by now we we have run 10K miles of gasoline through the engine and you can plant the throttle to the carpet at the traffic light with zero issues.
__________________
Always bring your A game.
1996 Flair 29V, 454 TBI, 4L80E. Your life is your story, don't let someone dictate your story.
@azmaddog I figured that same thing about the chassis, ours in indeed a 90 chassis/engine. I will double check to make sure there is no mechanical pump, but I am 99 percent sure that there is not.
@D Gardiner I have not been able to retest the fuel pressure, I did use the GM adapter that you referenced when initially testing, however I did my test directly after the fuel filter as I already knew the line nuts were free due to changing the fuel filter prior. Is it suggested to test the pressure directly before the TBI? During the test, I should be looking for 9-12 PSI, is that correct?
As for old fuel, I don't think that is the issue as it had around half a tank when we drove it home (about 60-70 miles at both city and highway speeds). When we put our 30-40 gallons in it was nearly completely empty and we almost didn't make it to the station, so not very much to dilute.
General: I mentioned we would be replacing the fuel injectors in my last post, which we did successfully. Upon replacing the fuel injectors, the engine ran beautifully, with only 5-10 instances of bogging down for a second or two, for about 10-15 minutes. At that point we decided, to clean up our remodel mess and reorganize our supplies and tools to prep for a short test drive (planned on about 10 miles to test). After letting the rig sit for about an hour to clean, we then started it up, moved it forward, put our Jeep in the parking spot, then went to take off only for it to immediately start bogging, sputtering, and falling on its face. Now it is back to being unable to stay running. What the heck?!
We did plan on replacing the Idle Air Control Valve, but I have not been able to find a replacement, the pintle on the original is about 1/4 - 3/8 inches longer than the replacements we have looked at, at NAPA, O'Reilly, Advance, etc. Does anyone have a GM, Delco, etc. part number for the IAC Valve?
As for the generator, I can't remember who mentioned this, but the fuel pump for it, where would that be located? In tank as well, or somewhere between the tank and gen?
On another note, not quite as crucial, but still obviously an issue. We have lost 12V power to both bathroom lights (vanity and shower) as well all the 12V lights going forward from there on the driver's side. We also have lost power to our 12V light in the "hallway" directly outside the bathroom door. The weird part about that is the 12V bathroom fan, still works perfectly fine.
From what I've be able to see GM no longer carries this part so aftermarket OE is the best you can hope for.
RockAuto.com gives the following numbers for an IAC under your year, chassis and block: Alternate/OEM Part Number(s): 17076228, 17090384, 17111788, 17113099, 19333272
It's a spendy part (Delphi) at $50.00. Your FI is a TBI 220? Maybe that makes a difference for the person at the counter.
I'm seeing a code 12 as an "All is OK" with the computer. If its running so poorly I would think something else would have cropped up. It sounds like a vaccum/gasket is leaking but you don't have a carbuerator. Do you have a vaccum booster for your PB or Hydroboost?
What is the make and model of your generator? A search with that info should tell you where your generator fuel pump is at.
My manual states fuel pressure should be not less than 9 and not more than 13 PSI.
You have put a lot of time and money into this. How close are you to throwing your hands up and taking it to a mechanic just to get the idle situation worked out? You've got more determination than me. Good luck.
At Slm32123:
Yes, your fuel pressure, for your model year would be in the 9-12 psi range.
Yes, please test the fuel pressure at the TBI unit. This way you can one 100% sure the TBI is getting the right pressure.
Because you are having an intermittent issue, might I suggest leaving the fuel pressure gauge and its adapter "On" the engine, then go for a drive, or two or three, until the bogging issue happens. This way you can determine (isolate) what the issue is.... either;
A) fuel starvation
or
B) electrical, ignition related
Place the fuel pressure gauge in such a way you can see what the fuel readings, from the drivers seat in real time. Did this often when I worked on cars back in the day.
____
As for timing jumping out of specification, it is highly unlikely, unless the bolt holding down the distributer is loose.
You can check for vacuum leaks with either carburetor cleaner (just be careful) or use a propane tester. Usually a vacuum leak will not cause a bogging issue. Normally vacuum leaks cause rough idling and miss fires.
Back fires through the intake (I assume you don't have this issue) was either bad valve seal or very retarded timing.
Also yes, Code 12 is the only code you should get under "key on / engine off" condition.
Retest the fuel pressure and watch the readings as you drive. Let us know what happened. We will get to the bottom of this.
__________________
Always bring your A game.
1996 Flair 29V, 454 TBI, 4L80E. Your life is your story, don't let someone dictate your story.
When I worked with my brother the sun machine came with a propane torch mix tip removed and hose on it. If you suspected lean condition feed tbi some propane if it smoothed out it was lean.
My 90s GM engines had EGR stick open many times. Usually after running on highway, the next start run like poo poo the early computer seemed to try to adjust and make it worse as it still ran bad hot. They made a gasket with screen to stop it from getting jammed. My guess would be eventually screen plugged and would delete the EGR. I would just pull the EGR and clean with carb cleaner it and make sure it was freed up.
Engine started sputtering and generator won't run after a fill-up. Sounds like bad gas. Every generator I've ever worked on had its' own fuel pump. A friend of mine, a Master Mercedes mechanic, yanked an engine out of his van and replaced it only to find he'd gotten a bad tank of gas.
I agree that gen has its own fuel pump, usually on the gen set itself. Double check for vacuum leak and EGR sticking. And just a thought, did you check/clear your air intake hose and filter? It almost sounds like you have something suddenly blocking your air intake and only intermittently. The only other thing that might be the problem, you sure don't want. You might have developed a stall problem with your torque converter or another tranny problem that is causing it to try and die when in gear. Check your electrical connections to your tranny and your throttle/kickdown linkage. And check that distributed to see if it has anything loose, inside and out. And if you have a rotor inside the distributor, check for loose or cracked. The only other thing I can think of is rust inside the gas tank that has broken loose and is intermittently plugging the fuel pickup inside the tank. After that, you are into electronics that takes special training/equipment.
As for your electrical problem, is your power distribution center on the opposite side of the coach from your power plug? If so, your system may crisscross several times under the coach. You could have had a rodent that chewed on wires and caused a short. Or you may have a leak that has gotten water into a connection. And trace your water lines while you are tracing your wiring. They didn't always used common sense when they put the plumbing together. At least they didn't on mine.
Hey all, thank you all so much for your help so far! I checked the EGR valve last night using the test methods mentioned on the website D Gardiner posted previously. Unfortunately my stupid butt thought blowing through the EGR was a good thing, but it means the pintle is stuck open. O'reilly has a new one for me and I will try putting that in this evening and see what happens. I will let you all know!
Sticking EGR: Yes, that can definitely explain the intermittent poor running.
If the EGR gets stuck wide open, it would greatly affect idle, and really mess with part throttle operation. It is quite possible that when the RV was running great the EGR pintle was stuck closed.
The EGR will not see part throttle vacuum until the engine coolant reaches operating temperature. Of course once the engine was at operating temperature the EGR could have snapped wide open and stuck there. Then later when the engine was off, and the EGR cooled its internal return spring could have (occasional) closed the pintle again,... it making diagnostic work fun!
Linear Mode
