I have been having occasional long crank/hard starting for about a week. Ever since I installed my MP-8 I have had this issue, it doesnt do it all the time but usually first thinhg in the morning or after it has sat for more than 4hours...it takes 4-5sec longer to start and it acts like it wants to in the normal time frame but sputters out and takes a little more.

I have removed the MP-8 and returned my truck back to my original settings...but to no avail. I am wondering if I might have blown my rail valve 2 weeks ago on the dyno. I was running Smarty TNT/R on RP-3 and made a run with the MP-8 on 100%.

What are some ways to test for a blown valve???

I can still make and maintain excellent RP just seems that the system bleeds down over time.

I also have NO rough idle or white smoke...and not making any oil!

 

Remove the return line off of the valve and see if fuel is dribbling out. If so it's bad.

MikeyB

 

If you can still get good rail pressure I doubt it's the valve. In my case at least the truck became very doggish and lots of smoke when the valve went bad.
mishkaya

 

careful though, i had symptoms of popped valve and pulled the return line to find it full of fuel. ended up being a false positive, had it tested and no leakage at all. guy at the shop said a little fuel can flow backwards through the return line and end up on top of relief valve....

 

when mine popped, i was going over a set of railroad tracks- felt like i'd pinned the pedal, but hadn't.... I looked back and there was a huge gout of black smoke in the road....

truck ran fine for the 12 miles back to the house. when i went to crank it, i had a long crank, followed by a smoky, not-all-cylinders-fueling-escalating-lumpy rise in engine rpm until i shut her down.

dealer said fuel rail had cracked.

Greg

 

you might also consider the possibility of a weak valve. Sometimes they can seal back up, but bleed off pressure at a lower psi.

just block the darn thing off and be done with it.

 

I agree!!!! I have had no problem with mine blocked and its been about a year now with no ill effects.

Joe

 

MP-8 on 100% with RP3 is no good...plug the valve!

 

Going to plug it tomorrow...anyone have pics of the process???

Links to pics of the process???

Parts list???

 

I'd just call john at floor it and get one of his. It's a nice solid piece, and it's only about 40-50 bucks. That way you don't screw up your stock valve.

 

I agree with jlibert , that's what I did anyway.
mishkaya

 

You don't screw up anything...just tap the banjo bolt!

The plug can be removed and all is normal!

Or...you can spend $50. lol

 

Just tap the banjo bolt and put in a steel plug. It will cost you a dollar and is reversable. That is how I did mine and it works great.

Joe

 

Less, I too have the same symptoms as you. 4-5 SECOND starts after truck has been sitting for awhile. Started after i installed and used the mp-8. Let me know how it turns out for you. I may try and cap my rail to and see what happens. Lets keep each other informed. I would like to see some pix or a write up on the process.

 

Wait, I have the dual feed line, I guess that eliminates the valve for me......