No Start when warm

[Militaryguy]

Hey guys I bought a 1995 GMC 3500 with the 6.5L and am having some issues with it.

When the truck has been sitting for a few hours plugged in or not (cause it’s that cold already in AK) it does a hard start and then runs fine at idle and with easy driving. When it’s be fired up no matter how long it’s been run and you shut it off it won’t restart for about an hour it just turns over.

Also when at a dead stop if I get on it hard it takes off fine and then once it gets out of first it acts like it is starving for fuel.

I replaced the lift pump when I first got it cause they guy said it was bad (test confirmed that) but other then that I have no idea what is going on this is my first diesel and every shop I call doesn’t know much about the 6.5

HELP please

[Robyn]

Could be several things..

Starter not spinning the engine fast enough ....

Injector pump is going south and cant build enough pressure to pop the injectors after the pump gets warmed up.

Somebody installed a set of high pop injectors on an engine with a worn pump

Low compression

If the engine spins pretty good speed on the starter...try adding a gallon of ATF to the fuel tank

Mix with diesel and then add to tank....This will THICKEN THE FUEL and if the rig starts better you have a bad INJECTOR PUMP

Any codes showing CHECK ENGINE LAMP ????

When was the fuel filter changed.

Be sure the lift pump is working.

LH FRAME RAIL INSIDE UNDER THE DRIVERS SEAT AREA.

To activate the lift pump on a 95

Park brake on

Tranny in D turn key to start.

Engine will not crank...but lift pump should run.

NICE PURRRRRRING SOUND ...AND YOU SHOULD GET FUEL FROM THE AIR BLEED ON THE FILTER IF OPEN.

Also WITH ENGINE RUNNING OPEN THE WATER DRAIN (Fuel FILTER) NEAR THE TOP OF THE WATER CROSSOVER AND YOU SHOULD GET CLEAR FUEL and engine should stay running...

If engine dies then the lift pump is not working.

Oil pressure switch near the glow plug relay at LH rear of intake manifold above the bell housing flange controls fuel lift pump.

Switch can die and the lift pump will not run.

If the lift pump is not running when the engine is running this can cause LOW POWER.

Run the engine and crawl under and see if the pump is vibrating.

Check for fuel flow at the drain even if the pump is running.

Filters are always suspect.

Add fresh filter (Clean out housing well)

Run lift pump with the tranny in D ENGINE OFF KEY IN START TO BLEED OUT THE FILTER

Get a helper....

Check the filter and lift pump.

I crudded up filter can and will cause terribly poor power..


If your filter is good and the lift pump is delivering fuel at the drain and the engine runs....and then things are still not good...proceed farther.


Let us know what you find

Robyn

[Militaryguy]

Engine spins fast like it should

Only check engine light that come on is when it’s going up a hil and throttle is over a 1/4 or going down the highway around 60 65 it pops on and off but it’s never stayed on

I’ll run the rest of the test on it probably tomorrow for the lift pump and other thing and let y’all know
Thank you

[Robyn]

If you are getting a check engine light there should be a code stored.

Pull the codes and see whats stored.

[Militaryguy]

Well now it’s not starting at all!

Went to work and was backing into a spot and it just died right there and came out to it this morning and no start at all it turns over great and I did the lift pump test and hear it running but no starting

[JohnC]

Does it smoke when you crank it over? If not then there's no fuel; either the fuel's not getting to the injection pump or it's not injecting.

Have you checked for DTC codes? Have someone crank it over while you look for fuel at the drain line.