I have a 94 Suburban with the 6.5 in it that randomly stalls. I went through the same issue a year ago and replaced the PMD and relocated it to the firewall. Everything was fine for the last year. Then in August if it was over 80 outside and parked in the sun it wouldn't start, but if I waited until it was dark outside it would start. Now that the temperature is cooler outside it starts no problem but randomly stalls. Sometimes it will restart right away sometimes you have to wait a couple hours. I replaced the PMD assuming that it was bad again, drove about 5 miles and it stalled again. I took it to a dealer to have it diagnosed and the best they could come with is they think the IP is bad, since they found metal shavings in the pump. The IP is a costly item to replace and not be sure, does anyone have any advice before I replace the IP? This truck has never had any biodiesel ran in yet.

ts
-sounds like an IP to me. tom

If the IP had metal bits in it then this is a no brainer. Fire it up and try to maintain 2,000 RPMs in neutral. If you can't keep it rock steady then it is the IP, though with bits in the pump I think that it is a foregone conclusion.

Bill

Make sure the lift pump, or pumps, are good. We had two IPs replaced under warranty before the dealer replaced the lift pump to solve the problem you describe.

I drove a 3500 silverado with a 6.5 for 8 years. Went through 2 IP's in that time. I have read about a lot of problems with them. Good luck.

The truck will hold a steady 2,000 RPM'S, no problems. How do you test the lift pump?

The 2,000 RPM test is used to prove the drivers and solinoids are working. That is usually what goes first. Theres a pigtail near the passenger side firewall (below the electrical buss and relays) that will give you a direct connection to the lift pump. Just feed it 12 V and you should be able to hear it running.

A good test is to start the engine and at idle, open up the fuel drain cock. If the engine dies, then the lift pump is dead. If no difference, then your good.

You will have to address the metal filings in the pump body. Metal filings are too big to get through the filter and even the intake screen so it has to be the internals of the pump. Somethings coming apart in there. You can diagnose until the cows come home, but if you don't find out where the filings are coming from your just running in circles.

Bill

When you turn the key on ,can you hear the lift pump running and when you turn it off it should still run for few seconds too.Try that first,a lot cheaper fix than the IP.Try your post here too a lot of very knowledgeable people there too on the 6.5.http://www.dieselplace.com/forum/forumdisplay.php?f=21