My '99 4x4 diesel used to fire right up , lately sometimes it has to crank longer than usual. Not real long cranking over, but noticeably a little longer crank time. Not all the time but did it today 3 times. It always fires though.

I dont drive it every day . Drove it last two days probably 200+ miles

I just put new batteries and military spec terminals and cables on it. Battery ground to frame and body grounds good. Has 164,000 miles, new VP a few years ago , lift pump pressure is ok, Fuel filter changed 5000 miles ago, and the old one was ok anyway . I run 2 stroke oil in the fuel all the time

I plan on putting a Fass pump on it but " Idont think" that is the problem

Any Ideas why it has to crank a little longer to fire sometimes. Or possibilities?

Any codes and what is OK fuel px?

Check for leaks or damp areas on fuel lines and fittings.  You may be losing your prime.

What's your fuel pressure during cranking? This will give a clue if there is air in the lines or not.

 

Is there any external fuel leaking around the head? Injection lines or the return lines? Remember the return is at the back of the and can only be seen from under the truck.

 

Suction leak? You'll need 2 people and pressurize the fuel tank after running. This will force fuel out a fuel line with a suction leak because now the lines are all load with fuel.

First thing this morning I checked for codes with my scanner. No codes, clear.

Turned off ignition, removed scaner, Turned ign on and fired right up like normal.

 

It seems after I drive it. Second , third time to start, It cranks cranks longer

 

Checked for fuel seepage yesterday on all injector lines and return line and "T" all are clean no sign of fuel leaks

 

Ive been meaning to buy and install a fass titanium, My replaced cummins stock LP was doing fine but I have noticed its lost 1 or 2 or so pounds of PSI . It doesnt go below 10 PSI though. I run 2 stroke oil/fuel

 

What's your What's your fuel pressure during cranking??

 

 

Fuel pressure is 12, 13,  ign. on, just before cranking, LP goes off, crank it and when it fires 12, 13 again

 

Where is the common place for a suction leak.

 

I had searched for a leak before extensively and did not find any leaks

Edited March 17, 201510 yr by GSP7

I would put money on your starter contacts. You can take it apart and clean it up and see if it makes a difference or you can order the rebuild kit from Larry B's and go that route. My .02.(and maybe prior experience)

This morning its firing up fast like normal 4 or five times tinkering with it.  Seems after I drive somewhere and then go to start again it does the long crank issue

 

Its kind of done this off and on for a year. Got the new batterys and redid mil spec terminals and cable ends I thought I cured it. But now its doing it again

I would put money on your starter contacts. You can take it apart and clean it up and see if it makes a difference or you can order the rebuild kit from Larry B's and go that route. My .02.(and maybe prior experience)

 The Starter motor works fine and cranks fine,  Doesnt have anything to do with the starter motor.

Edited March 17, 201510 yr by GSP7

Far as suction leak seepage loosing prime, I thought I had that is problem also,,, awhile back, about a year ago, I resealed the stock fuel filter rubber grommet on top , its nice and dry clean now

 

I wiped off the back of the head, where the return banjo is. Its real clean back there no sign of fuel seepage there either

 

Im stumped . Just seems like its loosing prime......

Oil test for diesel from injector leak?

Just talked to Eric from Midwest Fuel Injectoin.

 

Told me to look for air in tank return line, Put a clear hose in line to return to tank to check for air. All so said leaks will show no fuel seepage air can get sucked into the line causing loss of prime

 

Also said check injector connection tubes for seating

I went through this last year. Replaced all sorts of stuff thinking I was losing prime. Finally called BlueChip and explained to him and bought another VP and all is well again. If you're still running stock lift pumps I'd be concerned. Not trying to scare you but this was my experience. Got worse and worse until I just couldn't trust it anymore. Never had any codes.

The next time it does it dump cold water on top of the injection pump.... If it fires right up you probably should start looking for an injection pump. I suggest you support one of the vendors that support the site!

My VP44 only has 36k miles on it

Mine was supposed to have much less, which is why I fought off replacing it. If it's been starved for fuel and had a used PSG on it when rebuilt then 36k is not too new anymore. Heck I only got 96k out of my motor before the block cracked.Does your tach needle move when cranking? If not it could be a failing crank pos. sensor I've read.

.Does your tach needle move when cranking? If not it could be a failing crank pos. sensor I've read.

Read this and went out to look. It fired up so fast this time hard to tell but I did see it move off the stop before it fired

 

Didnt drive anywhere in it today but it has fired right up every time to day out by my shop. About 6 or 7 starts

 

This sucks that you dont have confidence in your truck

Edited March 18, 201510 yr by GSP7

Is there any external fuel leaking around the head? Injection lines or the return lines? Remember the return is at the back of the and can only be seen from under the truck.

 

 

 I re read this, Return lines are clean no leak,,, I was thinking about that,,, even if there was a return line that did have a leak it wouldnt effect starting... Agree?

Return line leaking will syphon the fuel out of the injectors causing extended cranking times. They can let air in the system without letting fuel out also, gives a way for air to get in allowing the fuel to drain back to the tank.

Edited March 18, 201510 yr by fire176969

Return line leaking will syphon the fuel out of the injectors causing extended cranking times. They can let air in the system without letting fuel out also, gives a way for air to get in allowing the fuel to drain back to the tank.

He's right, but yours does it when it's warm so I doubt it's a prime issue.

 

This sucks that you dont have confidence in your truck

A little hard to have confidence when it's a coin flip as to whether or not it's gonna start. But like I said another VP fixed mine. I'm perfectly confident now

I know you already said it isn't the starter, but I had the exact same issue as you explain. Cleaned all my terminals, Did good for a short time, then it went to sometimes it started immediately, sometimes I didn't know if it would of not. You said yourself you thought you cured it with new terminals, etc. If you have a new starter, then it probably isn't related and I won't mention it again. If you have some miles on it, I would at least consider it.