Engine/Transmission (1994 - 1998) '98 lift pump?

[hsmith]

Hook droped the truck at my shop today. '98 with 95K and no signs of any TLC given to the truck. No fuel at the filter. Worked with the primer pump a long time before finally getting the filter housing full. Still no start, but think the lift pump may be bad. Can not get any fuel through the P7100 at all. Isn,t this a little early for lift pump failure? Do I remember something way back about problems inside the tank for these models? The customer recently bought the truck and said when it runs it is a guttless wonder. All inputs welcome.

 

[Andy Redmond]

12 or 24 valve? 12 I'm guessing since you have a "primer bulb"



Also key on and "tut" the starter, but do not crank the engine, leave the key on and run out and look at the fuel shut off solenoid and assure that it is pulled up completely. If it does not move up or up all the way it can cause the no start or low power concern you described. (It attaches to the left rear corner of the injection pump).



If not search for posts on testing. . Usually the solenoid relay dies before the the solenoid itself. It is located on the firewall above the fuel filter can cause no starts/no engine shut off.



Crank it over and see what kind of pressure you have down stream of the filter. . at least 20 psi. Adapters are available to go in the banjo bolt (on the top of the fuel filter housing, nearest the injection pump). Remove the bleed screw with the 10 mm head (m6*1. 0 thread. . ) Maybe an auto shop will lend you an adapter and a fuel psi gauge.



If the lift pump tests ok and you can get it to crank, the overflow valve maybe stuck or have a weak spring lowering the fuel psi.



The DC service manuals give all the specs for testing for lift pump volume, ck. for excessive vacuum (fuel line restrictions) etc.



Let us know what it was.



Good luck,



Andy

 

[hsmith]

'98 lift pump

[Thanks Andy. I am an independent garageman with the necessary tools. Know about the starter contacts related to fuel solenoid problems. First thing I checked was that. This one acts like my '96 when the return hose was bleeding. The '98 uses different hoses so that is out. Really acts like there is a leak between the tank and lift pump. Trying to prime produces lots of bubbles. It will be a couple of days before I will be able to get it in the shop for a good check over.

Will keep you posted.

hsmithQUOTE]Originally posted by Andy Redmond

12 or 24 valve? 12 I'm guessing since you have a "primer bulb"



Also key on and "tut" the starter, but do not crank the engine, leave the key on and run out and look at the fuel shut off solenoid and assure that it is pulled up completely. If it does not move up or up all the way it can cause the no start or low power concern you described. (It attaches to the left rear corner of the injection pump).



If not search for posts on testing. . Usually the solenoid relay dies before the the solenoid itself. It is located on the firewall above the fuel filter can cause no starts/no engine shut off.



Crank it over and see what kind of pressure you have down stream of the filter. . at least 20 psi. Adapters are available to go in the banjo bolt (on the top of the fuel filter housing, nearest the injection pump). Remove the bleed screw with the 10 mm head (m6*1. 0 thread. . ) Maybe an auto shop will lend you an adapter and a fuel psi gauge.



If the lift pump tests ok and you can get it to crank, the overflow valve maybe stuck or have a weak spring lowering the fuel psi.



The DC service manuals give all the specs for testing for lift pump volume, ck. for excessive vacuum (fuel line restrictions) etc.



Let us know what it was.



Good luck,



Andy [/QUOTE]

 

[illflem]

If you can't find any leaks even on the steel lines, they spring them also especially at the welds for the hold downs, see if you get air with a full tank. There is a coiled pickup tube in the tank module and several close by self tapping screws that are known to puncture the tube, won't suck air till the tank level drops below the level of the hole.

 

[hsmith]

[Sounds like the ghost I am looking for. Finally had room to get it in the shop today. Had to replace the fuel pump on the old Scout (push car) so I could get it inside. Looks like I will be dropping the tank as I did not see any signs of problems with the outside lines. Should be getting with it tomorrow.



Thanks, hsmithQUOTE]Originally posted by illflem

If you can't find any leaks even on the steel lines, they spring them also especially at the welds for the hold downs, see if you get air with a full tank. There is a coiled pickup tube in the tank module and several close by self tapping screws that are known to puncture the tube, won't suck air till the tank level drops below the level of the hole. [/QUOTE]

 

[hsmith]

Re: '98 lift pump

Originally posted by hsmith

[Thanks Andy. I am an independent garageman with the necessary tools. Know about the starter contacts related to fuel solenoid problems. First thing I checked was that. This one acts like my '96 when the return hose was bleeding. The '98 uses different hoses so that is out. Really acts like there is a leak between the tank and lift pump. Trying to prime produces lots of bubbles. It will be a couple of days before I will be able to get it in the shop for a good check over.

Will keep you posted.

hsmithQUOTE]Originally posted by Andy Redmond

12 or 24 valve? 12 I'm guessing since you have a "primer bulb"



Also key on and "tut" the starter, but do not crank the engine, leave the key on and run out and look at the fuel shut off solenoid and assure that it is pulled up completely. If it does not move up or up all the way it can cause the no start or low power concern you described. (It attaches to the left rear corner of the injection pump).



If not search for posts on testing. . Usually the solenoid relay dies before the the solenoid itself. It is located on the firewall above the fuel filter can cause no starts/no engine shut off.



Crank it over and see what kind of pressure you have down stream of the filter. . at least 20 psi. Adapters are available to go in the banjo bolt (on the top of the fuel filter housing, nearest the injection pump). Remove the bleed screw with the 10 mm head (m6*1. 0 thread. . ) Maybe an auto shop will lend you an adapter and a fuel psi gauge.



If the lift pump tests ok and you can get it to crank, the overflow valve maybe stuck or have a weak spring lowering the fuel psi.



The DC service manuals give all the specs for testing for lift pump volume, ck. for excessive vacuum (fuel line restrictions) etc.



Let us know what it was.



Good luck,



Andy

[/QUOTE] Installed new lift pump today and primed system. Problem solved. Hard time convincing myself the pump was bad with the low miles. Now I am concerned about my own with 125K. Runs great, but would not want to be left beside the road somewhere.

Thanks for all the input, hsmith

 

[Andy Redmond]

Ck. valves hold no prisoners eh?



I would monitor fuel psi occasionally to warrant the changing of a good part. They often start to leak or at idle tap signalling there demise.



Good luck, Andy