83 6.9 fuel delivery problems
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Joined: Jul 2007
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83 6.9 fuel delivery problems
Hey all,
I'm having some serious issues with my 6.9 and fuel delivery. Funny thing is I have a friend with an '86 and almost identical issues. They both seem to run fine for about 5-10 minutes then start sputtering and lose fuel pressure. I've done quite a few things with mine and am about at a standstill.
Here's my list:
I've taken off the tank selector valve and blown air through all the lines in both directions and they all seem to be clear. I replaced the selector valve and installed a Holly Blue(110 gph 14psi) fuel pump directly after the valve. I had a new water separator, but actually ended up replacing it with a racor 490 water separator/filter w/primer pump. Here's where the story come in. I installed the racor unit to have a primer pump due to the problems I'd been having. I thought maybe the main fuel filter was clogging. When I first ran it, the lift pump pulled so hard that the primer pump on the filter unit was completely sucked down. I though maybe it required some extra help, so I added a small cheap pump which worked for no time at all. I then got the Holley and the truck seemed to do fine at first, but after driving it, I noticed it, completely sucked down the primer pump again. ( Note the primer pump is inline after the Holly High-flow pump) Here's the interesting thing. I can keep the Holly pumping and if I remove the feed hose to the Racor unit, I can hear it suck and then start pumping fuel. Then I can hook it back up and run for a few more minutes till it sucks dry again. I hope I explained what's going on well. It's a crazy scenario and one I've not seen before. It seems as if there is some sort of blockage, but I can seem to find it. Any ideas?
Thanks,
Mike
I'm having some serious issues with my 6.9 and fuel delivery. Funny thing is I have a friend with an '86 and almost identical issues. They both seem to run fine for about 5-10 minutes then start sputtering and lose fuel pressure. I've done quite a few things with mine and am about at a standstill.
Here's my list:
I've taken off the tank selector valve and blown air through all the lines in both directions and they all seem to be clear. I replaced the selector valve and installed a Holly Blue(110 gph 14psi) fuel pump directly after the valve. I had a new water separator, but actually ended up replacing it with a racor 490 water separator/filter w/primer pump. Here's where the story come in. I installed the racor unit to have a primer pump due to the problems I'd been having. I thought maybe the main fuel filter was clogging. When I first ran it, the lift pump pulled so hard that the primer pump on the filter unit was completely sucked down. I though maybe it required some extra help, so I added a small cheap pump which worked for no time at all. I then got the Holley and the truck seemed to do fine at first, but after driving it, I noticed it, completely sucked down the primer pump again. ( Note the primer pump is inline after the Holly High-flow pump) Here's the interesting thing. I can keep the Holly pumping and if I remove the feed hose to the Racor unit, I can hear it suck and then start pumping fuel. Then I can hook it back up and run for a few more minutes till it sucks dry again. I hope I explained what's going on well. It's a crazy scenario and one I've not seen before. It seems as if there is some sort of blockage, but I can seem to find it. Any ideas?
Thanks,
Mike
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 15
From: Nutter Fort, WV
Two things,
14 PSI at the IP is to much pressure, you should see around 6.
That much pressure is probably changing the timing.
Second thing, the electric pump needs to be mounted right in front of the fuel selector valve.
That way you are pushing fuel through the water seperator, not trying to suck it through.
14 PSI at the IP is to much pressure, you should see around 6.
That much pressure is probably changing the timing.
Second thing, the electric pump needs to be mounted right in front of the fuel selector valve.
That way you are pushing fuel through the water seperator, not trying to suck it through.
Laughing Gas
Joined: Jun 2007
Posts: 1,106
Likes: 35
From: Virginia
FYI- My understanding is that some of the Stonadyne pumps incorporate a fuel pump in the IP head, and a very fine screen. I have a pdf document of the pump break down, but I will need to make a jpeg to post it I think.
I recently have my pump apart, and my internal filter was spotless. It can certainly be done on vevicle, but it will be much easier if the pump is facing upwards on a bench or in a vise. They recommend replacing the filter with a "later version" if you replace it.
Check my gallery for the photos.
I recently have my pump apart, and my internal filter was spotless. It can certainly be done on vevicle, but it will be much easier if the pump is facing upwards on a bench or in a vise. They recommend replacing the filter with a "later version" if you replace it.
Check my gallery for the photos.
Last edited by Dieselamour; Jun 10, 2008 at 05:59 AM. Reason: add jpeg
