Engine/Transmission (1998.5 - 2002) 01 hard starting

[hbowers]

I have an 01 w/170k mi . it has a raptor lift pump and fuel pressure gauge.

it has good pressure 14 psi Idle. after it sits maybe 15 min you have to crank quite a while before it starts. when it does start it runs smooth as soon as it starts. I'm thinking it's leaking back between the vp44 and injectors. because if it were leaking back from vp44 to fuel tank it would get air and run rough at start. is it possible one or more injector tubes are leaking? I wonder how many would have to leak to cause the problem I'm having.

if anyone out there has had this problem I sure would appreciate your input. thank you

 

[FourBarR]

there is a check valve in the return line to the tank . its located on the vp-44 looks like a banjo bolt . There was a post a while ago with a picture of its location . could be stuck open allowing fuel to drain from the vp-44. Just a thought,easy fix if thats it.

 

[hbowers]

that's called an overflow valve. I tried a known good one. did'nt change a thing.

thanks for the reply

 

[JLandry]

hbowers,

Lot's of questions:

Are you saying the engine will start normally (quickly) if shut off for only a few minutes?

Did this condition come on gradually or suddenly?

How old are the injectors and the VP44?

After the engine has been shutoff for 15 minutes or more, if you bump the starter to activate the lift pump, does the fuel pressure come up quickly (1-2 seconds)?

Regards,

John L.

 

[hbowers]

starts normally if shut off for a few seconds. but after 15 min it's hard to start. condition came on gradually. had injectors last fall. don't know if vp44 has been changed or not.

but it has no codes. if you bump the starter pressure comes right up.

could one or more injector tubes be leaking?

 

[JLandry]

starts normally if shut off for a few seconds. but after 15 min it's hard to start. condition came on gradually. had injectors last fall. don't know if vp44 has been changed or not.

but it has no codes. if you bump the starter pressure comes right up.

could one or more injector tubes be leaking?

It sure sounds like it could be loosing prime somewhere in the high-pressure side of the fuel injection system, because from what you describe on the low-pressure side (fuel pressure rising quickly) that would seem to rule out any problem there.



If the injectors are newish, it's hard to imagine they're the culprit. And if just one injector tip were leaking (a reasonable scenario), then I would think the truck would still start reasonably fast but maybe would run a bit rough for a few seconds immediately after starting. What are the odds that several new injectors would start leaking causing hard starting? Pretty slim unless something terrible were done to the engine that you haven't mentioned.



When you say "had injectors," exactly what do you mean? Specifically, were brand new Bosch injectors installed (or some other high quality brand)? Or are we talking about throwing in some cheap no-name injectors, or possibly just some new tips in old injector bodies without pop testing and adjusting them?



Did you install the injectors?



Regarding the crossover tubes, if they're leaking I'd think you'd see a gradual rise in the crankcase oil level. Have you been watching for that?



Based on what you've told us so far, the most logical reason can think of for this problem is the VP44 fuel injection is simply wearing out internally and needs to be replaced.



A couple of little experiments...



Let the engine sit for awhile so the hard-start problem will occur, then bump the starter (without starting the engine) to activate the lift pump. Once you have full fuel pressure, try starting the engine and see if it starts any faster. If it does, this might suggest you're somehow loosing prime on the low-pressure side of the fuel-injection system.



Again, let the engine sit for awhile so the hard-start problem will reoccur. DON'T bump the starter to activate the lift-pump this time as in the previous test. Hold the accelerator pedal to the floor, crank the engine, and see if it starts any faster. If it does, this might suggest you're loosing prime on the high-pressure side of the fuel system.



Please report back the results of these tests.



Best regards,



John L.

 

[cerberusiam]

Does the FP run as soon as the key is turned on? You might need the flash to only run the FP for 2 seconds on start. The VP-44 has issues on warm starts if the low side pressure is too high.



Try this when its warm, disconnect the coolant temp sensor and see if that cures the the long crank.