8.1 Starting Wows

[Vroom]

Scott,
I'm waiting for delivery of the check valve. I'll get it installed and report back to everybody about my findings.

[M&EM]

Originally Posted by Ultra RV Tech

You would be on point if the customer had an '03 or earlier but being an 04 he has a fuel pulse dampener where the regulator would be and the regulator is in the fuel pump.

Jon, in 2004 and after, isn't the regulator part of the fuel pump ASSenbly in the tank and not actually in the pump?? If Vroom has normal line pressure, then I would suspect the check valve is still right at the outlet of the pump motor within the "pump/gauge/regulator assembly!! An external check valve should work any where along the fuel line to the engine.

Marty

[StevenRoger]

Going to chime in here on this one, My 2005 8.1 Bounder just started this hard to start concern after going down a long very washboard road in northern AZ this week end. Good to have such a great site to help find answers. The coach is not near me right now, and I haven't even started to dig into anything yet other than this, but could someone please tell me the numbers of the replacement fuel filter and pump assembly as I know they are most likely original. I'll start by replacing them just for good measure. Also, is the fuel pump in the tank?

[Vroom]

Here we go,
Got the check valve installed at the inboard side of the fuel filter. Started the rig and checked for leaks, dry with 63 psi. Shut it down and let it set overnight. Checked the f/p gage in the morning, zero. Tried to start it and it just cranked, second try it started. Checked for leaks, dry. I removed the check valve to make sure it was holding pressure, good. Could it be losing pressure back through the return line at the regulator? If so I would need to reinstall the check valve on the other side of the fuel filter just passed the return line "T". One more nutty thing, after removing the check valve I looked at the f/p gage and it was still reading 35 psi. Dose the fuel pressure damper continue to hold pressure at the fuel rails? Even after the fuel line has been separated? So, I'm going to reinstall the check valve a little further down the line to eliminate the fuel pump and his friends, check valve and regulator. I'm not going to do it right away as I'm willing to wait for feedback from everybody. I'm starting to think that my rig just might make a better hotdog stand. Thanks for your thoughts.

[M&EM]

It seems clear that the regulator also is leaking down with time. Best to locate the check valve forward of the return "T" of the filter.

If the FP gauge is connected at the shrader valve on the fuel rail, the valve insert may hold pressure on the gauge side of that valve.

[Vroom]

Good Afternoon,
Per my last post- After installing the fuel line check valve at the inboard side of the fuel filter I experienced no change in my hard starting problem. After thinking hard about the valves location in the fuel line and making the decision, with M&EM's blessing, to relocate the valve at the outboard side of the filter just past the pressure return line "T" the clouds parted and the sun shined. When I hit the key the rig started so quick I thought there was something wrong. So I let it set for two hours and tried it again, she lit right up. Still a non believer, I let her set overnight. 40 degrees first thing in the morning, now I'm a believer. It works, a $32.00 check valve from eBay and a $11.55 fuel filter from RockAuto. Thank you to every person that participated in this thread, amazing power in numbers.

[CJ7365]

Originally Posted by Vroom

Good Afternoon,
Per my last post- After installing the fuel line check valve at the inboard side of the fuel filter I experienced no change in my hard starting problem. After thinking hard about the valves location in the fuel line and making the decision, with M&EM's blessing, to relocate the valve at the outboard side of the filter just past the pressure return line "T" the clouds parted and the sun shined. When I hit the key the rig started so quick I thought there was something wrong. So I let it set for two hours and tried it again, she lit right up. Still a non believer, I let her set overnight. 40 degrees first thing in the morning, now I'm a believer. It works, a $32.00 check valve from eBay and a $11.55 fuel filter from RockAuto. Thank you to every person that participated in this thread, amazing power in numbers.

Wow, great news, I like to hear when someone spends some time trouble shooting and coming up with the solution, and it turns out positive.

Would be helpful if we saw exactly where you put the check valve, maybe a picture.

[AKIQPilot]

Great news Vroom. This should help any of us who may find our rigs hard to start. IT was the in tank check valve all along.

[boatman10]

wow thanks for all this information.....now i know that its just a check valve INSTEAD of a dying crank position sensor or cam posi sensor, which can both [and god only knows other malfunctions] give the same symptoms!!!!

i now hit the starter for just 2 seconds [after 5 seconds in the 'on' position to let fuel pump build up pressure]......then i do the 5 second thing again n then hit the starter it starts up immediately.

i'll do this until something changes then i will do the check valve....i got too many other projects going [like a complete repaint i'm HALF done with]

[4x4van]

Originally Posted by CJ7365

Wow, great news, I like to hear when someone spends some time trouble shooting and coming up with the solution, and it turns out positive.

Would be helpful if we saw exactly where you put the check valve, maybe a picture.

This is great info; although I don't have the problem, the knowledge for possible future issues is invaluable to us all.

Agreed; a pic (or diagram) of exactly where you installed the check valve, please!

Also, a link or part number for the check valve?

[GNICK]

Is there any way to edit the first post or title to indicate that a working solution was found -- thus enabling future readers to skip all the interim discussion and unnecessary alternative possibilities? (If you do, note that "woes" is misspelled.)

[boatman10]

turned out I have great fuel pressure all the time I checked it with a gauge....another tip-off was cycling the key to 'on' to run fuel pump for the 5 seconds it is allowed to run before start up did NOT help.

crank position sensor was a recall item on '01-'03 8.1L's...they are KNOWN to give a hard cold start condition.......I am going to replace that...its comparatively easy to get to thru the doghouse, is a KNOWN OEM failure item, and costs 25$ .

for some strange reason the recall was not to my knowledge extended to 8.1ls in workhorse.....you know they ALL had the same sensor.

I will report back.

[boatman10]

I knew mine was not a fuel pressure problem I checked it with gauge.......also squirting gas down the intake plenum did not help at all so it was not an injector timing issue [that would be caused by a bad CAMSHAFT position sensor] AND ALSO NOT a bad temp sender telling computer I had a warm engine when it was cold giving a lean-cold-start.

it HAD to be, In my case, the crank sensor.

I got mine 26$ delivered on EBAY.......you just need a crank sensor for a 8.1L most the parts places do not list one for the workhorse but a 8.1L IS AN 8.1L they all have the same sensor........and it does not matter if its a single oring or a two oring sensor both with work.

I carefully pulled it out threw the doghouse with PB blaster and a little pry bar then a big pair of channel locks twisting it slightly as I pulled UP.

now it starts cold at the turn of the key.

these CPS's do not throw a code til they are about dead.

there is a 'relearn' procedure for the computer.

warm up engine TO OPERATING TEMP n do a 'relearn' for the computer.....with foot on brake take warm engine to 5000+rpms, computer shuts down motor and you will see tach bounce from 4500-5000....let off throttle.... then n all sensors are 'relearned'.

foot MUST be on brake the whole time, engine must be warm n slowly take engine UP in rpms.