What next?

[Sickmaker]

My 99 3500, 5sp manual began having trouble starting about 6 months ago. I limped it along but finally broke down and replaced the lift pump and the vp44 this past weekend. Truck cranked great, ran great, killed, then cranked right up again. Today, I drove the truck about 6 miles, killed it, cranked it about 15 minutes later but to no avail. Waited, attempted to crank again, but nothing. 

 

The factory lift pump was replaced with an in tank pump before I bought the truck. I replaced the Spectra Premium SP7036M Fuel Pump Assembly and the vp44 with a Bosch from Thoroughbred Diesel.

 

I'm in dire straights here guys. I just dropped $1200 on parts, did the labor myself following 1973's guide to save the $2k labor cost. What do I check next?

[dripley]

Fuel pressure from the lift pump. Do you have a FP gauge? While they advertise the in tank pump for our years they are not great pumps for a VP truck. Dodge put one on my truck to the tune of $900+ 12 years ago. About a year later it was barely making any pressure.

 

Did you check for any trouble codes?

Fuel connections all tight?

Any fuel leaks?

Fuel in the tank?

Bad VP maybe?

 

Recheck anything you messed with during the install. Something may have come loose and you lost prime in the fuel system.

 

Also open a couple lines at the head and see if any fuel is coming out while cranking. No fuel no start

[Sickmaker]

Thanks dripley.

Fuel connections tight

No fuel leaks

Full tank of diesel this afternoon. It actually refused to crank at the diesel pump.

Vp looks brand new from Thoroughbred Diesel. Is there a way to test the VP?

 

I took the truck a couple weeks ago to a diesel shop near me and the mechanic gave me codes for fuel pump or injector pump.

[dripley]

Open a couple fuel lines at the head and see if fuel,comes out while cranking. Loosen the nuts completely and you should see a good stream of fuel. If there is no fuel it could be the vp or maybe the lift pump.

You can test the lift pump by bumping the starter, no engine start, and the pump will run for 20+ seconds. You have to get near the fuel tank but should be able to hear it run. Or you could open the drain on the fuel filter canister, do the same starter bump and fuel should stream out of it. That will make mess though without some thing to catch it.

 As far as checking the VP, Blue Chip Diesel has a very good trouble shooting guide for the VP. Far better than anything I could tell you.

[Sickmaker]

Good looking guide. I replaced the starter about six month ago, as soon as I had trouble starting, and put new batteries in after that. I will check the electrical though.

[Sickmaker]

Trucked cranked right up this morning. Drove it home, killed it and it would not restart. Then I did the lift pump check.

 

Lift pump runs great. I drained the fuel filter canister then cranked the truck, diesel poured out as I was cranking. 

 

Trucked cranked up after a few minutes but now, an hour later, no luck.

[Me78569]

just so we are all on the same page, when you say it cranked vs not cranked are you saying that sometimes the starter spins the motor over ( cranking) and sometimes when you hit the ignition the engine does not turn over at all? 

 

 

Or are you saying that it always cranks over when you hit the ignition but sometimes it starts and sometimes it doesn't?

[Sickmaker]

3 minutes ago, Me78569 said:

just so we are all on the same page, when you say it cranked vs not cranked are you saying that sometimes the starter spins the motor over ( cranking) and sometimes when you hit the ignition the engine does not turn over at all? 

 

 

Or are you saying that it always cranks over when you hit the ignition but sometimes it starts and sometimes it doesn't?

Sorry, it always turns over, but sometimes it starts and sometimes it doesn't, especially after the truck has been running and it hot.

[Me78569]

have you done a hot wire test on the vp when you get the no start condition?    If it doesn't start with hot wire you know the VP is bad.  That would be my guess.  If it does start then you know you have some sort of wiring issue.

 

 

 

Edited May 19, 2020 by Me78569