Engine/Transmission (1998.5 - 2002) another hard starting truck...please help!

[zman]

I have read just about every "hard starting" post I can find, but I still can't figure out what my problem is. I have had a hard starting situation for the past week and the problem started very suddenly. Prior to this, the engine fired immediatly but now it takes 7-8 revs to get it going. The fuel pressure goes to 1psi immediately following shutdown. Prior to this, it used to fall slowly to about 5psi and stay there. I replaced the fuel check valve on the VP44 last night, but I still have the same problem. One interesting note though, when I removed the check valve absolutely no fuel came out of the VP44 or the return fuel line.



The VP44 was replaced about 40k miles ago due to a bad solenoid. The lift pump was replaced about 6 months ago due to a leak. The current lift pump (my 5th) puts out around 15psi at idle and about 9psi WOT, which seems a little low to me for WOT. I don't see any leaks anywhere and all fuel fittings are tight. I don't have any unusual smoke when starting up, so it doesn't seem like the injectors are leaking. There aren't any codes showing up. The truck has about 85k miles on it now.





The truck seems to run fine once started and doesn't seem to lack for fuel or power when I turn up the Juice box. I haven't tapped the pump wire yet, so the pump hasn't been pushed overly hard.



Given what I have described, does anyone have any suggestions? This seems like a fuel pressure/pump prime problem but I don't know where else to look. Is the VP44 heading south? I'm going to unplug the Juice box tonight to see if that has any effect.



Any input would be appreciated. Thanks!



Steve

 

[Graphic man]

hate to say it but sounds like a VP44 going south



Scott

 

[SKneeland]

everyone is so quick to point fingers at the VP, when most of the time its a problem in the delivery system upstream



i had a hard start problem a while ago. turned out to be a small leak in the lines, so small it didnt leak fuel but sucked in air after the engine was turned off. if i started it right away after shutdown it would fire right up. if it was left for more that 10-15 minutes i had to crank several seconds to get it fired up.

in the end i changed out some lines and switched to a different connection style. i also put in a check valve just upstream of the factory filter, no more hard starts

 

[zman]

update...

I went out and bumped the starter to see what happens to the fuel pressure. Once the lift pump kicked on, it hit 17psi and stayed there. As soon as the lift pump shut off, it dropped instantly to 1psi, so something definitely isn't holding pressure. I'm wondering if there is a check valve in the lift pump, and if so, whether it is bad. If there isn't one in the lift pump, I'm wondering if there is one somewhere between the VP44 and the tank on the supply side.



SKneeland - Your problem sounds just like mine. Which lines did you have problems with and what was the nature of the problem?



Steve

 

[jdross440]

I had this happen to me about 3 weeks ago and thought my VP-44 was going bad. Come to find out, the passenger side battery would show 12. 5 volts until you put a load on it and then it would drop to 8. I disconnected it and left it overnight. It showed 12. 5 volts the next morning, so I hooked it up and disconnected the driver side. That's when I noticed the underhood light was dimmer on the passenger battery than the drivers battery. Low and behold using my digital volt meter you could watch the volts drop with just the load of the lamp. I pulled the battery out of my Roadrunner and put it in for a test and the truck started like normal. A new battery fixed my starting problem. Maybe you will be this lucky.

 

[SKneeland]

"Which lines did you have problems with and what was the nature of the problem?"



in an effort to replace the restrictive factory lines & banjo fittings, i had installed a solid, 1/2" stainless steel line from the filter housing to the VP(the one i installed from the fass to the filter held up fine). apparently it didnt take the engine vibration very well & was allways working just a little bit loose. i ended up getting some hoses made up with AN fittings instead for that section



i wouldnt hesitate to check all the fittings, including the ones on the return lines from the back of the head to the fuel tank.

 

[zman]

figured it out...

Well, it appears that the fuel pressure sending unit was the culprit. I had installed it about 4 weeks ago when I put my Juice box in. Since it was the most recent thing done that involved the fuel system, I decided to focus on it.



The sending unit came pre-coated with thread sealer and it was as tight as it could get but it sill managed to allow air in somehow (but no fuel leaked out). I pulled it off, cleaned off the old thread sealer, wrapped it good with some teflon tape and snugged it up tight. Problem solved. Thanks for all who responded!



Steve

 

[GKarpen]

Diesel fuel will over time eat right through that Teflon. You need to use a sealent.

 

[Timbeaux38]

What have you guys used to seal the connections with, I have a few seeping spots in my setup. No reall drippy leaks, but seeing wet connections is annoying.

 

[sg5054]

I haved used Rectorseal #5 for just about everything thats needs to have the threads sealed. I gave up on teflon tape years ago. It works on oil, gasoline, diesel, propane, saltwater, fuel oil, you name it. I wouldn't use anything else.

My 2 cents.

 

[Timbeaux38]

Can you find this at most hardware stores and such?

 

[sg5054]

yes, any good hardware store, Lowes, Home desperate etc should have it. It's nothing exotic.

 

[zman]

Thanks for the heads up on the teflon tape. I wondered if teflon would hold up. I'll try to find some of that sealant on my way home tonight. It looks like I'll have at least one more hard starting situation in the very near future... LOL.