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Discussion Starter #1
1.Lift pump test - See below​
2.Service Engine Light - Off
3.Model year 95
3a. Odometer reading 150000
3b. Miles on major engine components if been replaced
4.Do you have any engine codes? No.
5.If you do have engine codes - what are they?
6.Air Filter condition Clean
7.Fuel filter condition New
8.Condition of Battery terminal connections new cables, batteries, hardware
8A.Known condition and age of the batteries. 2 months
9.Upon cold start, does the radiator hose get hard quickly? About a minute
10.Upon cold start, do you have excessive white smoke? Yes
11.Do you have excessive cranking time before the engine starts? No
12.Have you used the block heater, and does this effect engine starting? No
13.During hard acceleration, do you have excessive black smoke? Little, not a lot
14.Do you have any unusual exhaust smoke issues? White smoke upon startup, no smell
15.Turbo check out - Pass
16.Do you have an EGR on the engine? (No
17.3500.
18.Indicate fuel that you are using: Bio-diesel, #2 Diesel, #1Diesel, SVO/WVO, other
19.Are you using any fuel additives? Licas upon last fill up, about 330 miles ago 1/4 tank remanining
20.Please indicate geographic region you are in: South Carolina
21.Do you have any service history available that might pertain to the problem you are having? No
22.Please indicate any modifications to the vehicle that might help us diagnose better. See below
23.Upon unscrewing the fuel cap, do you have a large vacuum formed in the tank? No

Did the lift pump test, it failed, replaced lift pump, restarted engine, redid test, fail again, tried 3 lift pump, fail again. I have 12 volts going to the lift pump. Each time the engine stalls right around 30 secs. I can not see 2 new lifts pumps from seperate places being bad. On another issue, my temp guage is going up tp 250, then comes back down to about 180. Only does this on the first 5 mninutes of driving, no boil over and can not see any leak, no anti-freeze in oil. Any ideas, suggestions, 6.5 TD dance that I have not done yet.

I have learned a lot of info from this site, thanks in advance.
 

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I would check all grounds connections, battery connections and cable conditions. If you are not getting fuel from the tee when the truck is running I would be looking at the oil pressure switch even with voltage showing at the pump.
 

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I would check all grounds connections, battery connections and cable conditions. If you are not getting fuel from the tee when the truck is running I would be looking at the oil pressure switch even with voltage showing at the pump.
What Dmitch said.
 

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Yep, sounds like you could have an oil pressure switch problem there.
 

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A healthy IP will pull it's own fuel so a bad OPS or LP will cause top end performance issues, but should not keep a truck from running, unless a partially blocked fuel filter is adding to problems reducing IPs ability to self draw fuel. bad LP or OPS does need to be fixed, with other problems cited I'm with the check wiring recommendations as well if youy have 12v then other side of LP power is the gnd circuit side which is notoriously poor on GM trucks.

To confirm the bad OPS, "hot wire" the lift pump with a jumper to power lift pump temporarily for direct to 12v with ignition on source, and separate ground to the pumps gnd lead to frame, if powered direct and you have stumbles then OPS isn't culprit.

A fix I use to help gnds on GM is to add a double ring lug battery cable put one end to a stud on the block, and the other end to a stud on the frame, Alternator mount on engine is a place I like to use, the factory braided main gne is uninsulated & corrodes easily, plus low mount beside the starter is hard to see/monitor for cleanliness.
 

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Discussion Starter #6
Had voltage going to lift pump, checked current, almost nil current, replaced OPS, truck can hunt again and barking like the mad dog she is. Ain't no kitty in this engine. :) Just glad I got it fixed, before the IP went out or it broke down onlast nights date.
 

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On another issue, my temp guage is going up tp 250, then comes back down to about 180. Only does this on the first 5 mninutes of driving, no boil over and can not see any leak, no anti-freeze in oil. Any ideas, suggestions

Thermastat is sticking closed for 5 minutes or you have air in the block, this can score cylinder walls when the rings seize from heat.
 

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On your over heating issue, you can experiment, but you will still have to buy a new thermo(IMHO for this buy OEM or Heavy duty Stant) A trick used by Stock car racers is to gut the thermo stat so that all remains is a flat plate with a hole in it (use side cutters to cut the arms off the thermostat and the "door" and wax pellet assy will fall off) If you remove the thermostat completely you will have an overheating or super cold running engine depending on certain running conditions. the "plate" acts like a restrictor, the plate exact same as when the thermostat is open at operating temp, the only problem with this plate trick is if will take much longer for your engine to come up to operating temp...BUT in your case will elimanate the sticky thermo to confirm if this is your problem, which I suspect it is. to eliminate air I always remove the hose or sensor that is at the highest point on the engine and still behind the thermostat, once I had a Firefly that I had to fill the coolant system thru the heater hose to eliminate the air pockets.

This trick works well when you are stranded on the side of the road with a suspected stuck thermo and a hot hot engine
 

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Discussion Starter #9
Well fixed the overheating problem and thanks for all the suggestions. Coolant is full, my temp sensor in the on head was bad. Installed new one and guage works fine now. WOOHOO.
 
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