Engine/Transmission (1998.5 - 2002) Replace ALL return lines?

[Froadin]

Has anyone replaced ALL their return lines? I mean from the fittings out.

I started having a hard start issue after it sat for a while. Then it progressed into something that might only take 30 minutes to happen.



I have been running the dual LPs and the full Vulcan setup for a while now, and it started one COLD morning. I have looked over everything, and the only thing that I can find that is seeping some is the T in the return line.

I pulled the check valve and it seemed to be working fine, but I couldn't test it throroughly.



Either way, I have not been able to find anything specific that is causing it to happen, especially so fast as 30 minutes!



I am starting to think about replacing the entire return line setup. I hate to start working on one part of it, and keep chasing my own tail and finding more problems.



Ideas? Comments?

 

[NoSeeUm]

Hmm... .



I am not understanding how a problem in the return line can cause a hard start?



Jim

 

[rweis]

I replaced my return lines if you want to get into the how, but I do not see how the return line would cause hard to start. The return line is not pressurized and in the stock configuration dumps the return fuel back into the fuel pickup cannister.



Sounds like air in the system somewhere, now where?



I do know that when I work on my fuel system I plug the input to the Vp44 because there is a fuel reservour right there under the electronics bay cover (the ebc is the top cap to the internal fuel chamber). Maybe fuel is leaking out of the VP44 backwards down the fuel input system and the VP44 input fuel chamber is not full at startup. Just a thought.



Bob Weis

 

[Brand-X]

Sounds like he thinks the fuel is draining back to the tank. I have been dealing with the same thing for some time I have the RASP my truck would fire up then run out of fuel. I put a check valve from a detroit in the fuel line it is to early to tell if it helped as the problem is inconsistent ... George

 

[rweis]

Maybe wrap every fuel fitting in paper towels (zip tie them?) and run that for a day or two (so it would show wettness) to see if that would yield anything.



Bob Weis

 

[timbo]

Has anyone replaced ALL their return lines? I mean from the fittings out.

I started having a hard start issue after it sat for a while. Then it progressed into something that might only take 30 minutes to happen.



I have been running the dual LPs and the full Vulcan setup for a while now, and it started one COLD morning. I have looked over everything, and the only thing that I can find that is seeping some is the T in the return line.

I pulled the check valve and it seemed to be working fine, but I couldn't test it throroughly.



Either way, I have not been able to find anything specific that is causing it to happen, especially so fast as 30 minutes!



I am starting to think about replacing the entire return line setup. I hate to start working on one part of it, and keep chasing my own tail and finding more problems.



Ideas? Comments?

I to, do not think you have a return line issue. Sounds like air, what kind off pumps are you running and is one pump bigger than the other? It is poss. to cavitate the second pump if it is bigger than the first pump. Also,depending on what type of pump like a holley, it can suck air at the shaft seal but not leak fuel. I would sugg. pressurizing the system,cap it off up at the vp 44 and put air press in the suction of the first pump. use a guage and a ball valve. pressurize to 5-10psi close the ball valve and watch for press. degrade and look for leaks. hope this helps.

 

[Froadin]

I have the 7 psi carter LP and the stock compaign carter LP. Both are on the frame rail in front of the tank. About 2 feet apart.

All lines on the suction side are new 1/2" lines from vulcan. I did not reuse the rearmost section of stock hose like the normal big lines kits do, I got extra line and replaced that as well.

I have checked and snugged up every fitting I could find. Nothing was loose enough to suggest air getting in either.

I was thinking it was return line because the check valve on the vp44 seems fine (not entirely sure, just did a simple fast check on it). And the fuel is draining out of the system.

How I have to start the system. I bump the engine to run the LPs for a few seconds and let them build full pressure (20 -21 psi). I then turn the motor over for a few seconds before it attempts to start. I find it starts a little easier if I push in the throttle some.

I will often let it stumble a second trying to start and stop cranking it, and just let the LPs run for a few more seconds before trying again. It will start after a few seconds, and will stumble/stutter for a second or two, then smooth out and run fine.

I do not have any hard running issues. Seems to run fine.

I haven't changed ANYTHING on this system for a couple months now, and it just started doing this a week or so ago. At first it would take all night to cause the hard start issue. But it slowly got worse until now it only takes about 20 to 30 minutes before I have problems with it.

 

[timbo]

Now that i think about what your describing, it sounds like you may be onto something with the return line thing. With those pumps you have, fuel can backflow through them. If you have a leak anywhere in system it could potentially draw air in, when you shut it off, since the IP pump is higher than the tank. maybe try putting a inline check valve on the outlet of the lift pump. so no drain back can occur. Still suonds like an air leak into the system. Somehow.

 

[Froadin]

I am not beyond doing something like a check valve.

The odd part is that the system worked great for months. Then it started this.

My first guess was that the check valve at the VP was bad and allowing for leakdown.

So I pulled it out, cleaned it up a little, and put some air to it. I couldn't regulate it very well at this low pressure, and my rubber end piece had a leak, but I got the valve to fully open up around 18 psi.

I couldn't tell if I had a leak in it cause of the rubber fitting leaking air. And it's hard to hold the fitting, air chuck, cover the leak in the chuck and try and cover the little hole in the check valve.



Btw, why the heck does it have that little extra hole in the bolt that doesn't have any way to stop fuel from leaking past it? The spring loaded ball seems to work and move fine. But that extra little hole bugs me. Doesn't seem right.