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Replaced IP, still hard starting hot.

S

scubabri

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Hemet, CA
I just replaced my IP with a reman from pensacola. My PMD is on the front bumper. Just got done pulling from Redding, temps outside were in the high 90's to 100. I pulled over and the truck sat for about 15-20 minutes and when I tried to start it again, it cranked for probably 6 or 7 seconds and then fired.

When its cold it fires right up.

I replaced the IP because it wouldnt start hot unless I dumped a bottle of water over it, then it would fire right up.

Other than that, the truck ran a lot better now that I have the GLE chip in it. I'm running sustained up a hill about 9lbs of boost, and on the flats about 5 lbs, towing a 12k fiver.

b
 
scubabri said:
I just replaced my IP with a reman from pensacola. My PMD is on the front bumper. Just got done pulling from Redding, temps outside were in the high 90's to 100. I pulled over and the truck sat for about 15-20 minutes and when I tried to start it again, it cranked for probably 6 or 7 seconds and then fired.

When its cold it fires right up.

I replaced the IP because it wouldnt start hot unless I dumped a bottle of water over it, then it would fire right up.

Other than that, the truck ran a lot better now that I have the GLE chip in it. I'm running sustained up a hill about 9lbs of boost, and on the flats about 5 lbs, towing a 12k fiver.

b
Click to expand...

Sounds like air perhaps. Run a clear tube (vinyl tubing from Home Depot) on your fuel return and look for air bubbles.
 
So I just went out and tried to start it, its been sitting for maybe 40 minutes, wouldnt start, dumped water over the IP and it started right up... still air bubbles?
 
well I wouldnt assume that right off the bat. Did you correctly time the IP, or do you know what the TDCO was on the old one before you replaced it? Did the problem start after the GLE reflash?
 
Yes, correctly timed it, its currently sitting at -1.94 tdco (the tech at Jefferson State Diesel in Redding was a saint for letting me instruct on the finer details of timing). the old one had a tdco of +.024 (GM Service tech was clueless). I replaced my old one for essentially the same problem, no start when hot. This one seems a bit better. I did notice more power before the GLE and after the new IP, and after the GLE there was a pretty big difference in power. I just got done towing from Redding down to SoCAL. Made the grapevine at about 25mph, in 2nd gear, about 9 psi boost, temps stayed right at about 200-210, outside was about 65 deg.

I'm putting 16 oz of walmart 2 stroke in for every full tank.

I really hope its not bad, because I cant do the work myself (no place to work on it) and I paid $500 bux to have it replaced (that included putting in the FTB). So I'll be very upset if its indeed bad. I didnt have the cash to get the one from heath, and I was worried about catastrophic failure of my old one on my trip home.

Since the water "trick" worked, I cant think of anything else up there that would react to the water trick. As I said, my PMD is on the front bumper.
 
While this won't help your current situation, it may be the underlying problem:

How's the lift pump?

Is it producing enough pressure for the engine?

Got a gauge on it?

Is it running at all?

While the IP can draw fuel through the lift pump if bad, running it hard and heavy with no fuel pressure from the lift pump could have cooked your new IP head and rotor on your last run.

Worth checking....
 
last I checked the pressure was about 5 psi at idle. I'm out driving around, just did the lift pump test, opened the water drain, steady flow of fuel and engine kept running, had it open for 60 secs or so. I don't have a way right now to check pressure under load, spent my wad on getting ip replaced. could the lift pump be bad and still pass the test?
 
scubabri said:
last I checked the pressure was about 5 psi at idle. I'm out driving around, just did the lift pump test, opened the water drain, steady flow of fuel and engine kept running, had it open for 60 secs or so. I don't have a way right now to check pressure under load, spent my wad on getting ip replaced. could the lift pump be bad and still pass the test?
Click to expand...

If you had no issues towing I doubt its a lift pump issue, especially since it passed the test.

Anyone with internal knowledge of the IP's know the reasoning why the water trick works?

How has it been recently? Any change in attitude?
 
Matt Bachand said:
Anyone with internal knowledge of the IP's know the reasoning why the water trick works?
Click to expand...

Excessive clearances in the rotor and head assembly. Increases when warm and the pump has trouble building pressure after bleed down. When it cools, clearances tighten up and the pump can build enough pressure during cranking for light off.

Pouring water over the pump cools the assembly and tightens up the clearances when hot.

So the theory goes....sounds counter intuitive that clearances would be tighter when cold and looser when hot but that's how it's been explained to me....
 
Was that timing done with the Snap On? Because if you read it on the Snap On then it may not be correct. It would more likely start hot better if the TDCO was set more like -0.75. Not that the -1.94 is bad, just might start easier at more retarded position when cranking. But first you need to verify what the TDCO is on a Tech 2 or CC or AE.
 
we tested it with both the snap-on and my car-code, they both agreed. As far as altitude, I was in bakersfield, ca, so pretty much sea level. I've been driving it all day today, so far no problems starting. I'm still concerned, but I'll give it a few days. The only difference was the temp in bakersfield, close to 100, where here now I'm at 1300 feet and temps are in the mid 80's. I did notice that with my old IP, the hotter the day, the harder the start. But always water got me running on the old one. So I carried around 3 gallon jugs of water to make sure I didnt get stuck.
 
Have to drive it a little so all the air is out of the system. Make sure to put 2 cycle oil to increase fuel lubricity and help breaking in. Some people even put non-detergent motor oil.
 
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