Engine/Transmission (1998.5 - 2002) Help for friend's '02

[dmclaughlin]

A friend of mine is having problems with his 2002. I'm not familiar enough with the 24 valves to help much, so I want to post and see if anyone on here might have some answers.



All summer he pulled his boat to the lake and the truck ran fine. Since then he has only put about 100 miles on the truck. Driving it over the last couple of days, he says it has lost all low end power. It is extremely doggy at all rpm's under 2000. Get the truck over 2000 rpm's, and it seems ok. He can't figure it out. He does all his own service and changes fuel filter with every engine service. The only thing he is going to try is to change the fuel filter and see it that helps. The truck is completely stock with no gauges.



TIA!



Dave

 

[Mishkaya]

Does he show any codes doing the key trick?

 

[JLandry]

Dave,



Have him check for trouble codes either using a code scanner or by turning the ignition key ON-OFF-ON-OFF-ON (leave ON) in rapid succession. Any stored trouble codes will be displayed in the odometer window so he should be prepared to write them down. Report back here what he finds and we'll try to help.



He should also check fuel pressure present at the fuel injection pump inlet (the Bosch VP44 radial pump). A fuel pressure test kit can be purchased from places like Harbor Freight Tools or eBay for under $25. Ideal fuel pressure is about 15 psi at idle (a little more is even better) and NEVER under 5 psi under any circumstances. Usually the lowest fuel pressure will be when accelerating with WOT (Wide Open Throttle).



Sometimes engine power can be affected by such things as a faulty MAP (Manifold Air Pressure) sensor, a faulty IAT (Intake Air Temp) sensor, or a faulty coolant temp sensor. A malfunctioning fuel injection pump can also cause low power.



Best regards,



John L.

 

[dmclaughlin]

Update

Talked to my friend last night. Neither the key trick nor his mechanic's computer shows the truck throwing any codes. His mechanic is sure it is the lift pump. Guess the mechanic is recommending an Air Dog to replace the factory lift pump. The mechanic also wants to install an Easy (don't know which one) that will have guages with it. Hope my friend goes along with the Easy install, that way he will have guages in the future to help him diagnois problems. Thanks for all the replies!



Dave

 

[hsmith]

Lost boost maybe???

 

[monkeyman]

If your friends truck is an automatic, tell him to go to autozone, and get the speed sensor that goes on drivers side over drive housing, its $13. 00 there. I think its a one inch socket
It will not throw a code, and mimics: Bad injectors, Bad VP44, Bad Fuel, Bad TPS, take it from me, Im on my third one! Change quick as fluid drips out when removed, takes three minutes, Rick

 

[dmclaughlin]

Thank's ... but....

Monkeyman,



Truck is a 6 speed. Thanks for replying.



Dave

 

[JLandry]

His mechanic is sure it is the lift pump.

Dave,



That doesn't seem to make sense. If the lift pump were underperforming (can't keep up), it would tend to affect power output at higher rpms before it would at lower rpms.



The lift pump could indeed be bad, but I doubt it's the cause of the symptoms you've described. In any case, a simple fuel pressure test would quickly indicate if anything is wrong with the lift pump.



In the absence of more information, I'm still voting for an underperforming sensor (MAP, IAT, or coolant temp) or a faulty Bosch VP44 fuel injection pump. Sensors giving erroneous signals don't always trigger a fault codes.



Best regards,



John L.

 

[dmclaughlin]

John,



I agree with you John, if the lift pump was bad, why poor performance at low rpm's and normal at higher rpm's. Don't know for sure if the mechanic did pressure test the fuel system. I'm sort of thinking not. I think he just crawled under the truck and listened for the lift pump to work when my friend turned the key on.



I haven't talked to my friend since the beginning of the week, but I will pass on what you are thinking about a bad sensor. I also don't know for sure if he is going to go with the Air Dog and Easy box. Ah yes, gauges on that truck sure would help out right now. Hope he at least ends up with some sort of gauge package. If it is a bad lift pump, this will be the 2nd one he has put on the truck. The next time it might mean a new VP44 (if not already).



Dave