Think I figured out my weird restart idle issue...

[Alexia]

Background and Partial Remedies:
Ever since getting the stroker running along with a fuel cell gas tank in the MJ's bed I get this weird stumble and erratic fuel trim happening when starting the engine within one to two hours of shutting it off. I thought it was the classic #3 injector heat soak issue so I wrapped the injectors. However, it seems to related to too much fuel being delivered in bursts. I noticed that the rubber fuel line at the pump would bulge slightly as the regulator primed then stay that way bulging more after restart.(In testing it would just keep inflating the hose if I kept turning the key off and on to prime it.)

So the issue is definitely one part that the hose is failing or not up to the task of handling 50 PSI at a minimum. I ordered some quality parts from Earl's/Edelbrock to replace it.

Question:
Is it possible for the pressure regulator to fail in such as way that it appears to work normally, but continue to build excess pressure past its specification? At least I know the pump is working strong.

 

[O-Gauge Steamer]

As can be the case for any regulator, the two failure modes are low and high. Whilst a high pressure failure must be a rare occurrence, it is certainly in the realm of possibilities.

IMO, the two repair choices would be either a new pump or an external pressure regulator.

I have to ask here, did you get he Sprintex installed?

 

[Alexia]

As can be the case for any regulator, the two failure modes are low and high. Whilst a high pressure failure must be a rare occurrence, it is certainly in the realm of possibilities.

IMO, the two repair choices would be either a new pump or an external pressure regulator.

I have to ask here, did you get he Sprintex installed?

Parts arrive Wednesday for the fuel line so I will find out. This MJ has to run reliably for a while since my LJ's engine is knocking.

The Sprintex is not yet installed. Just scared of how it will handle running around 14:1 SCR on 93 octane. A lot of knowledge I have researched says it should be fine.

 

[O-Gauge Steamer]

Rule of thumb says to reduce boost by one psi for every point increase in CR with a 9:1 as the base point. If this is accurate, then the "normal" 10 pound boost level for a non-intercooled SC installation would be reduced to 5 pounds. This is assuming no water/meth injection.

At issue is detonation control. At higher CRs, this rapidly rears it's ugly head for a non-intercooled setup.

My partner and I are about to start an SC installation onto an engine with a 10:1 CR.

I hate to quibble, but you know how it is with a "rule of thumb". Usually, they hold up. I would most definitely install a knock sensor to aid the tune.

All in all, should make for a real stump puller of an engine.

Please keep me informed on your progress. It is an interesting project to be sure.

 

[Alexia]

I removed the old fuel injectors while going to transfer the fuel rail to the supercharger manifold. Chunks of crud fell out and the top of the injectors were gunky black. After six rinses of lacquer thinner it is coming out clear, but now all the paint is falling off getting chunks everywhere.

I will run a few gallons of fuel through the lines into a bucket to help purge anything that might still be floating in there.

 

[cruiser54]

From the tank?

 

[Alexia]

From the tank?

Nope, the inside of the fuel rail is rusting. I pulled a good replacement from the junkyard and still plan to purge the lines from the tank for caution.

 

[cruiser54]

That's pretty weird..

 

[Alexia]

That's pretty weird..

I was aware the fuel rail had some outer rust on it so I completely sanded it, sealed, and repainted it back when I did the original 1997+ conversion. It was just worse than visually obvious at the time.