Lets see if my diagnosis is correct..............100 degrees is the killer.

[mattplumber]

So its been hot here in memphis this week. Damn hot. The temps have broken 100*+ for several days in a row. Its been in the high 70's low 80's at night.
My truck has developed an intermittant hard start issue that seems to be heat related. The truck has started fine in the mornings after sitting all night, and during the day off and on making service calls. Where its become a bear to start is when it has been sitting all day at my office in the sun. When I would start it to go home in the afternoon it would start and then die, symptomatic of air intrusion. After cracking the injector lines and cranking over I have had fuel almost immediately at the injectors. After several 30 second cranking sessions at wide open throttle it would finally start up and run fine.

So im thinking my injection pump may be the culprit. Can the temp outside cause heat soak issues even if its been sitting all day? I have ruled out air intrusion because it starts after sitting all night. Unknown miles on IP but it looks to have been replaced before. 235k miles on the truck.

Caps and lines have been recently replaced, olives, lift pump, and hoses as well.
No idea on ip and injectors though. The truck does run well when it runs though..........
It also seems as if i have a small fuel leak at the advance piston on the IP though. It has leaked for some time now but never seemed to cause any starting issues. Could heat cause this small leak to exaggerate itself enough to cause a hard start?

So if it is infact my IP, im going to take it off and have it rebuilt at my local stanadyne shop, Taylor Diesel.
I might be able to put the ip off of my old truck on it in the meantime (92 7.3 N/A). Is this doable, however temporary it may be? If I can do it with no ill effects, should I turn up the fuel screw a flat or so to compensate for it not being a "turbo" pump? Also, the 92 truck entered a runaway state when the headgasket? went. Would that cause the IP to in effect destroy itself? Just trying to get all the facts out there so I can get the best help from the community here, which I appreciate so much.

So thoughts? Am I thinking in the right direction?

 

[seawalkersee]

IP problems can compound when there are other problems. Is your lift pump good? Are you sure there is not an air problem? There should be no leak at the IP no matter how small. You will be able to put the NA pump on the turdo enging without problems.

Should not have been affected by the run away condition that I know of.

Be sure to mark your housing where the timing mark is on the old one to get it close.

SWS

 

[Shadetreemechanic]

if the ip head is worn you can help it out by increasing the viscosity of your fuel. Adding Veggie oil, motor oil, and/or tranmission fluid to the tank helped me get another year out of my ip.

 

[mattplumber]

At what ratio does the mix become "thick" enough to show results? Veggie oil is probably the cheapest route to use as a thickening agent................as I dont have any oil or atf filtration equipment.

 

[Shadetreemechanic]

At what ratio does the mix become "thick" enough to show results? Veggie oil is probably the cheapest route to use as a thickening agent................as I dont have any oil or atf filtration equipment.

That depends on how worn out your ip is.
Id start with 10-20% and see if that fixes your problem. Then go up from there.
When I was trying to stretch the life of my ip it eventually got to the point that it wouldn't start well cold on 80% VO. But toward the end of its life I was pouring anything in the tank I could find and some of it was not filtered well.

 

[Russ]

sometimes if it is a heat soak problem with the IP,if you pour cool(not ice cold) water on the pump it will start. Easy cheep thing to try.

 

[RLDSL]

Heat can mess you up sometimes. we get heat around here that really goes beyond insanity . that 100 deg once you calculate in the true heat index is really more like 125 deg. the saturation effect it has on things in murder. There;s a reason people drop dead every year in this region when the temps climb into that range, and folks out in the desert can't understand what the problem is, because they can stand under a tree and all is good. in this humidity, there's no getting away from it and it gets worse at night. Metal parts swell like crazy trying to throw off heat with forced air blowing the moisture saturated blast furnace air across the parts. If you have something that is going to be prone to heat swelling failure, then you are in the right place for it to happen.

 

[mattplumber]

Did the cool water trick, but it didnt do anything. I guess its time to change out an IP.

 

[Shadetreemechanic]

The cool water trick works pretty consistently in my experience if the problem is a worn head in the pump. If it didn't help I would verify lift pump pressure and lack of air intrusion before spending on a pump.

 

[tonkadoctor]

The cool water trick is what we had to do to hummers often over in the sandbox and it works.

We found it usually takes about a gallon to cool it off enough on the GM 6.2 - 6.5. Probably similar on the IDI as it takes more to cool it off inside than many think it does.

 

[mattplumber]

Maybe I just didnt pour enough water over it. Unfortunately I never know when its going to act up so I end up having to bleed it down anyway when it starts and dies. Lift pump is brand new, so I dont think theres an issue there. It just seems to me that the IP would be much hotter and less willing to pump fuel after the engine has been run and then shut off for 30 min- hour or so. Ironically it starts fine in that situation. It would also seem that if its been sitting at my office all day even in 100 degree heat that the IP would be alot cooler than it would after shutting down and re-starting.............its been a long week and my mind is on overload so sorry if what im trying to say isnt making sense.............

 

[OLDBULL8]

Do you have the heat liner attached under the hood? Setting in the Sun, the underhood temps might reach 300*, even while running the underhood temps can reach that, then when the engine is shut off the temps rise considerable. Cheap trick is to add a couple of gallons of ATF to a half tank. If that does it then your IP is worn out. Try it.

 

[Agnem]

DON'T POUR WATER ON IT. IT'S NOT A HEAT SOAK PROBLEM.

Two reasons:

1) - You said it starts then dies. This IS an air intrusion problem. Cracking the injectors open serves no purpose.

2) - Heat soak only happens when the external surfaces of the pump heat more rapidly than the internal ones. A pump that has been basking in heat of any temperature will eventually stabilize internal and external expansion. If the insides are the same temp as the outsides, then heat soak doesn't happen. It's only when the outside is super heated while the inside stays at a lower temp that this problem can occur.

The fact that you recently replaced your return lines points to that as the source of your problem.

 

[mattplumber]

Mel- When I said recently replaced, I meant within the last 4-6 months. I did the return line kit back in march or april I think and have not had issues with that since. The most recent problem I have had is with the lift pump. I replaced it maybe 3 weeks ago. Its been starting fine since then. Can extreme heat exaggerate air intrusion problems? Im just asking because the situation is definitely heat related. No doubt in my mind. The only place that I can clearly tell that is "wet" with diesel fuel is the advance piston nut and arm, but it has been this way since I got the truck. I have had oil pooling in the back of the valley for some time now which I had begun to believe was the oil drain grommett for the turbo. Looking at it now, it looks as though its a compound leak. Both diesel from the advance piston & oil from the drain as well as the mix doesnt smell like diesel but is definitely thinner than engine oil. Could the high outside temps make the small leak at the advance piston expand/contract enough to allow a sizable enough amount of air in to cause my problem?
Sorry for asking so many questions, just tired of replacing unnecessary parts that seem to solve the problem, but then it returns again. Kinda frustrating.

 

[Agnem]

Sure. Temperature is a big factor with return lines and air leaks. Everything expands when it gets hot, and you have a bonified leak. Here's the thing about ANY fuel leak on these engines. If fuel leaks out, air MUST leak in. Simple physics. When your IP leaks, air goes into the pump. It could just be that the leak has gotten bad enough now that the air is going where it hurts the most. I wouldn't worry with anything else until that pump is repaired or replaced. Always fix what you know is broke first. An obvious problem is a blessing.