M1009 FUEL PRESSURE

jmas24

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Hello,

Fairly new to the forum and the M1009. Especially fairly new to diesel engines...

Spring 2019 (yea i know) replaced a rusty gas tank in the blazer. Thought it would be a simple fix and needless to say she's still not on the road... I have had multiple mechanics stop and play with it and nobody can figure it out.
Since replacing the gas tank and re-bled the lines, the 6.2 diesel will idle but will lose fuel pressure or what we assume suck air somewhere and stall out. After a new injector pump (which the old one was probably fine), 3 fuel filters and all lines checked for air it will still only run about 4 miles and will not take on any hills before it stalls out. Dropped the gas tank multiple times to check the filter, replaced fuel pump and have 10PSI, changed the diesel in the tank. We are running out of options... Any thoughts or tricks?

1986 6.2L Diesel M1009 on 35's with 6" lift.

thoughts on the replaced rubber line collapsing? Should we switch that 4 foot of rubber back to metal? Thought about an electric pump? Just want to get her back on the road.. ran COMPLETLY fine before the first mechanic replaced the fuel tank. Could it be the wrong tank? wrong size sending unit? anything?
 

Barrman

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Try removing the fuel cap and running it. It could be a fuel tank venting problem. Otherwise, I would suggest following the steps in the -20 manual trouble shooting section exactly.
 

jmas24

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Try removing the fuel cap and running it. It could be a fuel tank venting problem. Otherwise, I would suggest following the steps in the -20 manual trouble shooting section exactly.
Have bled the system countless times and let it idle etc.. have also ran with the cap off and changed caps. Dropped the tank twice and Changed vent line. Gas cap spring is clean and working . Originally we thought it was just an air lock issue but weren’t sure how that was affecting the diesel motor.
 

dependable

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Make sure fuel return line is working. If you used proper 3/8ID fuel line, the 4 ft of rubber should not be a problem. I'd check to see that none of the lines are pinched. Did you make sure pick up tube did not have any rust or debris in it when tank was out?

One test you can try is to put compressed air into fuel tank, blocking fill hole w rags, and see if you can detect any leaks.
 

jmas24

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Make sure fuel return line is working. If you used proper 3/8ID fuel line, the 4 ft of rubber should not be a problem. I'd check to see that none of the lines are pinched. Did you make sure pick up tube did not have any rust or debris in it when tank was out?

One test you can try is to put compressed air into fuel tank, blocking fill hole w rags, and see if you can detect any leaks.
Will give that a shot.. haven’t found any leaks but again I guess hard to tell if it’s so small..
 

jmas24

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when applying 10 - 20 PSI on injector return line with air, fuel will prime and start but still dies after 90 seconds. Just bought k&n 10psi electric fuel pump and am trying to find time to get it installed.
 

Tinstar

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I assume your mechanical fuel pump is working?
If it’s original to the truck or you haven’t replaced it since you’ve owned it that might be the issue.

Their a total pain to change but inexpensive.
 

jmas24

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I assume your mechanical fuel pump is working?
If it’s original to the truck or you haven’t replaced it since you’ve owned it that might be the issue.

Their a total pain to change but inexpensive.
Just replaced mechanical pump thinking it was failing.
 

cucvrus

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OK. Have you double checked the mechanical lift pump? They have 2 that fit and only 1 is correct. The one you want is the one with the pumping action resistance taking place immediately upon compression of the lever. the incorrect one the pumping action takes place deeper in the compression cycle of the arm and the 6.2 does not have an eccentric with a high enough lobe to depress the fuel lever far enough. You need a CHFP 906 fuel pump Delphi. If you have a 0030 you have the incorrect pump.
 

jmas24

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OK. Have you double checked the mechanical lift pump? They have 2 that fit and only 1 is correct. The one you want is the one with the pumping action resistance taking place immediately upon compression of the lever. the incorrect one the pumping action takes place deeper in the compression cycle of the arm and the 6.2 does not have an eccentric with a high enough lobe to depress the fuel lever far enough. You need a CHFP 906 fuel pump Delphi. If you have a 0030 you have the incorrect pump.
Correct pump, the 2nd one. Got the k&n 7-10 psi electrical pump on this weekend and it runs better than before I had all this trouble. Not sure what changed from just changing the gas tank. Left the mechanical in place for now until it fails, then I’ll block it off.
 

jeffhuey1n

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You are describing a problem I had with my 1009. I troubleshot the fuel system components one time at a time. Everything was fine until I found that the original filter was a pos. I removed it and replaced it with a round, screw in type filter and mount. I haven’t had a problem since then.
 

jmas24

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You are describing a problem I had with my 1009. I troubleshot the fuel system components one time at a time. Everything was fine until I found that the original filter was a pos. I removed it and replaced it with a round, screw in type filter and mount. I haven’t had a problem since then.
Ran the same when I bypassed the filter as when it was hooked up. My next step would have been the filter.
 
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