Snowturtle
Registered User
Thanks, I'll pick up a gauge today!
That's a thought, maybe I'll take it out and try again. I haven't been to town to buy a pressure gauge yet - I assume if it's in wrong it won't be pumping? But I do get fuel out of the schrader valve when it's running...While it should be 5-7psi the IP only needs a couple PSI at the inlet. I can't recall for sure but I seem to remember someone posting specs on an e-pump thread that even 1psi at the IP was adequate. I've run a lot of miles with a wimpy Facet that definitely does NOT give 5-7psi across all RPMs and if I keep it floored in 2nd gear or 3rd on a long climb t doesn't take long before the FuelFilter light illuminates but there is no chugging or hopping. You can still drive with a failed lift pump as the IP will, at great cost to itself, suck fuel from the tanks but it won't take much throttle before the filter light illuminates. The only time I noticed any behavior like you describe was when I still had air in the lines. Of course I have no idea how you might get air intrusion below 2000 RPM and then have it seal above 2000 RPM. Any chance this could be a case of the lift pump installed improperly, as in the arm is below the camshaft instead of on top?
I like the thought, I can't see any reason other than fuel supply. I'm going to go pull that out and check it. That could also explain why it took me a while to get it started when I first finished the work. Maybe at higher rpms the IP sucks hard enough to supply itself but not at low rpms. Thanks for the input!Think I have it backwards--the pump arm rides BELOW the cam.
That's a great idea, I hate those olives!I suppose one of the next moves would be to run some fuel line from lift pump to a can of fresh diesel and see if the behavior changes. It sure sounds like air intrusion but it's odd that the truck starts right up normally. I've read some folks install a clear piece of fuel line before the IP so they can check for air bubbles in the fuel. I prefer rubber fuel line on the lift pump outlet to fuel filter inlet anyways because you get rid of that hard line and it's olive seal.
I got my injectors from Russ, I'll check his site for those lines. ThanksThere are lift pump to filter and filter to IP lines made by Russrepair known here as @typ4 to get rid of the olives, if you have a 6.9 or early 7.3 there is still one olive from the IP to the metal return line on the drivers side of the engine that runs back.
I prefer the later style return line, 89.5 and newer.
Holley e pumps do not seem to seal worth a damn, so when they ho out in my experience you get a large vent to atmosphere, causing your truck to run like crap and then die
I got rid of the filter on the engine. On the frame, about about halfway between tank and IP, I have a Racor 2 micron filter, then a supply pump. I have the original vacuum switch after the supply pump.While it should be 5-7psi the IP only needs a couple PSI at the inlet. I can't recall for sure but I seem to remember someone posting specs on an e-pump thread that even 1psi at the IP was adequate.
Square cut o-rings inside the brass fittings on both sides of the stock filter and the IP inlet. I think just those 3 total. They get hard over the years and brittle, leak. It's HARD to get them out once they get really hard. But as a PM no big deal if the previous owner actually did it. I had to burn mine out the first time I changed them. Eventually deleted them with better stuff.What are "olives". On the van and my cars supply lines are 3/8, return are 5/16, and all the hard connections are brass compression.
I think the inlet to my IP was a solid connection, not an olive - is that what Kansasidi was talking about? We're talking about the line that runs from the filter to the center of the IP between all the injector lines, right?Square cut o-rings inside the brass fittings on both sides of the stock filter and the IP inlet. I think just those 3 total. They get hard over the years and brittle, leak. It's HARD to get them out once they get really hard. But as a PM no big deal if the previous owner actually did it. I had to burn mine out the first time I changed them. Eventually deleted them with
If its a formed steel line, there's an olive under the connection nut. Was a factory installed part.I think the inlet to my IP was a solid connection, not an olive - is that what Kansasidi was talking about? We're talking about the line that runs from the filter to the center of the IP between all the injector lines, right?