Engine/Transmission (1998.5 - 2002) Hard start - with a twist!

[deezuldon]

'99 2500 2WD, auto. Lately hard starting... cranks for 7, 8 seconds and then lights off. Has always started within a 1/2 revolution until recently. (260K miles. ) Now sometimes it will light right off, sometimes not. If not, extended cranking as noted above. Then always runs great. On shutting down same scenario. Could be only two minutes between shut down and start-up: crank, crank, crank. Better when cold, but not always.



Until recently! Turned on the A/C to deal with warm weather locally - and it starts right up EVERY time as long as the A/C is on. Turn the A/C, off, and it's back to extended cranking.



Say what? Doesn't make sense! Seems to indicate an electrical problem as opposed to fuel... but how can the A/C be connected to starting?



For the record, have a reman VP44 ready to go in, have something over 100K on present VP44. First one lived for 150K +/-. Will replace fuel lift pump at same time.



Don't know what pressure existing LP is putting out, don't have a gauge. But would seem "adequate" at least, as once it's started, it does fine, even under load.



How can the A/C possibly eliminate the hard start? That's a weird one... .



Any ideas?

 

[ThrottleJockey]

'99 2500 2WD, auto. Don't know what pressure existing LP is putting out, don't have a gauge. But would seem "adequate" at least, as once it's started, it does fine, even under load.



How can the A/C possibly eliminate the hard start? That's a weird one... .



Any ideas?

Here's an idea.



Get some gauges. Gauges are wonderful diagnostic tools, as opposed to mere speculation.

 

[PRout]

Here's an idea.

Get some gauges. Gauges are wonderful diagnostic tools, as opposed to mere speculation.

Ditto on the above. Fuel pressure gauge is one of those "must haves" for a VP44'd truck. It might give you a clue

Speaking of clues, you might use a code scanner and check for errors. You might find your answer there.

Other than that, thats a good one. . Thats going to be bugging me also to figure out the connection. .

Just one question, Are you sure it is related to the A/C setting, or could it just be a coincidence?

We WILL figure out the connection, Im sure of that. Just need some time and possibly more input when asked.

 

[Joe Mc]

the main question here seems to be "when A/C is switched to on - ther's no hard start, why?"



Well, that's a darn good one . . Any electrical Guru's out there with an answer for this fellow? I'm just curious as all hek at this point too? ? ?

 

[deezuldon]

Thanks guys.



Seems absolutely to be linked to A/C being on. That's why it doesn't make much sense. If I turn the A/C off: crank, crank, crank. If the A/C's on, or more specifically if the clutch to the compressor is engaged, then she fires right up.



Has not thrown any codes at all.



Yes, ther'es always the chance that it's LP related, but if that truly is the case, then why does it start right up only with the A/C on? That to me, seems to be electrical, not fuel. And since she runs fine at all rpms regardless of load... ?



The only guess I can make is that it finds a stray ground path when the A/C's on? But even that doesn't make sense!



???

 

[PRout]

Thats a good one. . Might want to check all the grounds. Possible bad ecm or programming. Might want to try programming it with a smarty just for grins & giggles (although those are hard to muster sometimes).

Hopefully, someone has seen this before and will chime in.

Someone with a hot box (VP44 tester) could plug the tester in to the back of the VP eliminating the vehicle's wiring, ecm, etc, and see if that makes a difference.

 

[obert]

Hmmm. Maybe its more to do with the call for a/c than the load of it.



I'm reasonably shure the compressor clutch wont engage untill ECM/PCM see oil pressure. My '98 is that way, at least.



Now to set down with a schematic and scratch your head for a while... .....

 

[DFerverda]

I had some hard starts like you describe, i changed the batteries, it made no difference. Then i changed the starter, that did it. The old one had 190k on it and was just weak. No problems since, it pops right off with 1/2 turn of the motor. I also would clean and grease all the grounds.

Dirk