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Problem Still Happening

OBD-II at least in my 98 is in the underhood fuse center in front of master cylinder, the cover should have the fuse/relay identification schematic in it's lid, I'd run outside and grab a picture, but we have monsoon type rain going on rite now. IIRC relay is 1st one in the row closest to radiator.
 
Found it and it looked good, no corrosion on the prongs. Any way of testing it? The fuel shutoff solenoid stayed in the open position while hooked up to a battery charger for an hour and a half but I took the plunger out anyway. Going for a test drive!
 
MAGNUM SERVICES said:
Found it and it looked good, no corrosion on the prongs. Any way of testing it? The fuel shutoff solenoid stayed in the open position while hooked up to a battery charger for an hour and a half but I took the plunger out anyway. Going for a test drive!
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Just do simple lift pump test will prove your LP ok. That relay does not have anythign to do with the Injection Pump fuel.
 
LP failed as did my test drive! Ran great for about ten minutes and as soon as I hooked up my trailer and pulled onto the road it quit! Still no codes or engine light. What brand LP does anybody recommend? Mine was replaced under warranty on 1/28/09 from Autozone and I will take it back to get my money back and buy one from somewhere else.
 
Since you're in a jam, and probably don't have time for Walbro FRB-5, I'd go AC_Delco and order for a 93. Was around 120 I think. Otherwise, go anywehre, and order it for a 93 so you get the HO version, and plan on doing Walbro down the road, as I have heard nothing good about non Delco LP's...

When my OBD2 quits due to low fuel pressure it does throw a code though, can't remember which one, but it's an IP code that indicates soemthing's wrong with fuel and puts it in limp mode before actually dying.
 
Are you sure you don't have a clogged sock in your tank??

Its free and easy to do, just take off the LP inlet and blow compressed air into the tank with fuel cap off.

Either way, when you're replacing the LP you should do this, just to clear the sock out IMO.
 
The LP relay sure does have to do with injection pump fuel, it power the LP during operation, well it should. And the OPS is there for backup and to prime system after shutdown.

If you want to make sure its working, just undo LP harness under truck and put multimeter across the harness contacts and read voltage when you turn key to on, and see how long voltage stays with IGN on.
 
buddy said:
The LP relay sure does have to do with injection pump fuel, it power the LP during operation, well it should. And the OPS is there for backup and to prime system after shutdown.

If you want to make sure its working, just undo LP harness under truck and put multimeter across the harness contacts and read voltage when you turn key to on, and see how long voltage stays with IGN on.
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Tested LP with a light and it was on for about three seconds then went out. After the truck started it stayed on the whole time but my truck vibrates alot so I could not tell if it was still running.
 
Matt Bachand said:
Are you sure you don't have a clogged sock in your tank??

Its free and easy to do, just take off the LP inlet and blow compressed air into the tank with fuel cap off.

Either way, when you're replacing the LP you should do this, just to clear the sock out IMO.
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Will blow that out tomorrow as it is getting dark and its dinner time. Thank, Keith
 
MAGNUM SERVICES said:
AC Delco # EP 158 but it does not say if it is a H.O model.
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It isn't per-see an H.O. unit, but ordered for a 93 mechanical IP truck gives it a higher output than the DS-4 non mechanical pumps (94+) they are exactly the same plumbing wise.


I didn't mean to mislead saying LP Relay has nothing to do with fuel to IP. I thought he was diagnosing no fuel to his IP, and starting to mess with shut-off solonoids and other parts on his IP.

I thought he thought the LP relay would help his I.P. get the fuel demand from the puter.

The LP circuit and proper fuel output from LP should have been squared away and passed before messing around with anything I.P. related.

Sorry for the confusion.
 
Also I agree that a fuel pressure guage (which can be had from Harbor friegt or other places for around 10 bux) is a must have for any 6.5'er.

In fact, I believe all 6.5'ers should have an in cab gauge for fuel pressure.


When my truck dies first thing I do is crack that fuel bleeder to see if it sucks in. Usualy when IP is starving for fuel it creates a vacuum, and opening the bleeder lets air go IN to fill the vacuum.

Upon next re-start, I would crack the bleeder again and make sure fuel comes out, and the truck doesn't stall.

If it stalls when bleeder is opened, there is inadequate fuel pressure, weather it be due to a clogged fuel sock, bad lift pump, or any other issue.

Thats the easy test without a gauge. Sometimes it will pass this test, but still not enough adequate fuel pressure for proper operation, thats where a gauge becomes necessary.

At least the easy test gets you in the right direction, and all it requiress is popping your hood and turning the bleeder. Can be done at anytime, even broken down in middle of traffic.
 
Matt, thanks for the info on the LP. Hopefully KOI auto parts has one tomorrow in stock, then I will look for the receipt from Autozone to get my money back. Again, Thanks, Keith
 
New LP installed! AC Delco # 158 for a 93 GM 6.5! 4 psi at idle! Open bleeder screw on filter and plenty of fuel comes out and the truck stays running! I hope this is the end of my problem! Will keep you all updated! THANKS to ALL who replied! Keith
 
4psi is low for that LP, could point to a clogged tank sock. Or as I saw the other day an IP moving too much on the return line.

Also try it with the fuel cap off.
 
MAGNUM SERVICES said:
New LP installed! AC Delco # 158 for a 93 GM 6.5! 4 psi at idle! Open bleeder screw on filter and plenty of fuel comes out and the truck stays running! I hope this is the end of my problem! Will keep you all updated! THANKS to ALL who replied! Keith
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Same LP i have, i get 8 at idle and 5-7 driving with instant recovery.

Did you blow your sock?
 
buddy said:
4psi is low for that LP, could point to a clogged tank sock. Or as I saw the other day an IP moving too much on the return line.

Also try it with the fuel cap off.
Click to expand...

I am going to try a different gauge as this one is old and the glass is broken so I will question its accuracy!
 
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