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Hello forum. Bob here

Bobrl

New Member
Messages
14
Likes
8
Location
Staunton il.
Thread starter #1
I hope all is well to all! Beautiful day here in Illinois. I have problem with a newly purchased 92' chevy 2500, 6.5 turbo. F in the vin. I purchased it on a nice warm day and drove it home , around 100 miles. No issues except transmission when cold shifts veryhard! After warm up shifts good! So monday this week i drove for first time after drive home , and it was hot out, say 90 ish. And it started fine and i drove say 12 miles and at location it was idling for maybe 10 minutes and when i moved it and braked hard it stalled. Wouldnt restart. Waited a few minutes and it did start, when i went to move it seemed to surge a bit. Then got on the road a 1/8 mile and it stalled while driving. After few minutes it restarted (had hood open) drove say 10 miles, came in to town and it stalled three more time (same as before). Finaly got it home!! Tests i have done 1- fuel pressure at T drain line cranking is say 7-8 psi. Running it drops to 3 psi at idle and at 1500 rpm it goes below 2. I disconnect the suction side of lift pump and put hose in a bucket of fuel no change. My question is will the values of th lift pump cause the stalling and very hard restarts that day? Starts fine now st my shop. Thanks for any hepl!!! Sorry for so long a post!!!!
 
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13,092
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3,216
Location
alaska
#2
92 is mechanical injection pump. #1 cause of issues is air in fuel. Put a clear piece of 1/4" tubing on the return line coming out of the injection pump to be able to monitor for air. When it's not running a bubble in the top of the tube is okay. When running no bubbles no matter how small are permissable.
 

Bobrl

New Member
Messages
14
Likes
8
Location
Staunton il.
Thread starter #5
Hello. Thanks for getting back to me!! So a clear tube off the front of the ip to ?? Also where to connect the pressure gauge between the filter and ip ?? It shut down couole time today and i removed the vent plug from top of filter and got suction sound and i unscrewed the filter housing itself and it was almost empty of fuel, that was right after it shutdown!! I had left the key in the on postion when it shut down , and the filter was empty. I shut key off, removed filter housing and turnd key back on and it filled the chamber. Not sure what it is!!!! Thanks.
 
Messages
13,092
Likes
3,216
Location
alaska
#7
On the clear tube your replacing the one closest to the fan. Sounds like an obvious fuel issue. Not real familiar with the 92 but.... assuming it's like the 93 I believe the LP is controlled by the OPS (oil pressure sender). I'd start by replacing it and doing an OPS relay mod.
 

THEFERMANATOR

FRANKENBURBAN
Staff member
Lead Moderator
Messages
9,151
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2,619
Location
ZEPHYRHILLS FL
Staff #10
It sounds like somebody wired your lift pump to the key switch if your filter housing filled with just turning the key on. Sounds like your sucking air somewhere if your filter is getting air in it. You need to get that fixxed before doing much else as running an injection pump dry is a good way to tear one up.
 

Will L.

Well-Known Member
Messages
8,076
Likes
7,292
Location
Boulder City Nv
#13
Here is a video showing a clear hose installed on a running engine with a HORRIBLE amount of air in system. Truck was crazy hard to start and could barely keep it running.

Any hardware store has the clear tube. Only need 6” piece and it is 1/4” hose.

Now, there are other possibilities, but do this first. Dont buy liftpump or anything yet. Just do the clear hose for now. We will respond quickly.

 

Bobrl

New Member
Messages
14
Likes
8
Location
Staunton il.
Thread starter #14
Ok. I have some clear tubbing am installing today !! How would you go about finding air leaks??? I also have a 1958 GM 4104 , 6-71 Detroit , Gray Hound RV with the same issues!!!! Thanks so much!!!!
 

Bobrl

New Member
Messages
14
Likes
8
Location
Staunton il.
Thread starter #15
Hello. Installed clear tube. No bubbles at any time. Idle , rev up, clear fuel! Also i but the drain hose , off of T vavle into a clear bottle and started up engine, opened vavle and nothing comes out!! Not even a drewl !!! Shut off engine and turned key on to start and it filled a 12oz. Bottle in say 10-15 sec. with a milky look ! I guess the filter bowl on the truck hasnet been draind lately!!
 

1994ch

Active Member
Messages
460
Likes
248
Location
South Carolina
#16
Sounds like a problem with the power getting to the lift pump. Not sure on the 92, but on my 94 the lift pump only runs when there is oil pressure. I think in 95 or 96 they started making the lift pump run for a bit before engine start to build up pressure for an easier start.

Anyway it sounds like maybe someone has wired in an aftermarket way of running the LP but the Oil Pressure Sensor is not keeping it running after you start it. I am looking for a diagram..............
 

1994ch

Active Member
Messages
460
Likes
248
Location
South Carolina
#17
Found a couple wiring diagrams.......was going to post them and then realized it violated the copy write. However you can go there yourself and get them for free http://www.wilsonautoelectric.com/TSB_Database_License

When I looked up 1992 6.5 the wiring diagram had 6.2 in the top right corner so you might want to look at the 93 6.5 as well. Either one should be close enough to get you started down the right path.
 

Bobrl

New Member
Messages
14
Likes
8
Location
Staunton il.
Thread starter #18
Ok. I just signed up for the service. Thank you!!! I am always looking for wiring diag!!! For every thing!! I know there is a lift pump relay (factory) on the firewall on the passenger side, under the plastic cover. It i belive is brought on with a contact in ignition switch at start up, when i turn key to start , lp comes on, stays on then i start engine and the ops takes over!! Suppose to anyway!!! I ordered a new lp, ops , and i think i might order Leroydiesel lp mod with relay and wts and a primer momentary sw. for priming after filter change. Sound good!! $135.00 though!!! Oh well. Thanks again.
 

Will L.

Well-Known Member
Messages
8,076
Likes
7,292
Location
Boulder City Nv
#19
Yeah, Leroy’s harness is the way to go. Not sure if will solve current issue.

That clear tubing on th ip, just leave it for future diagnoses. It will need replacing every 3 years or so but is worth it so that anytime youbhave a hiccup you can just pop the hood and see any fuel flow or air intrusion issues.

Did you dash mount fuel pressure gauge I hope? What does the pressure do as the problem is occurring is the question.

Stock style liftpump only buy an AC Delco ep158.

Something else is happening here, but I am missing a clue.

Any other fuel line besides clear needs sae30r9
 
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