My Granddads truck is getting low on power, it starts, runs, idels fine. it just wont hardley do 75 anymore it takes it awhile to get there. I know its alot of miles but Im thinking its low on fuel pressure? lift pump? let me know what yall think? It doesnt use too much oil?

 

leaky intercooler maby?. might be new injector time. its hard to say without any guages to look for indicators

 

Fuel pressure could be a problem but it could be either the lift pump or the OFV. I would replace the OFV first since based on the mileage on the truck it probably needs it anyway. Another thing it might be is a clogged cat (assuming its still on there).

 

I think the cat is still there, OFV? just a year ago with just a few less mile it ran fine this truck doesn't do much anymore, so?

 

Yeah, the Over Flow Valve. It is what makes a restriction in the fuel return line to give the injector pump the fuel pressure it needs. Get something to drink, make some popcorn, and do a search on it. Once you see how many hits you get you'll see what the popcorn and drink are for.

A quick and dirty way to see if its the cat is to disconnect the exhaust at the turbo and take it for a quick ride. If the truck runs OK then you know its a problem in the exhaust. If it still is weak then you have a problem elsewhere and if it were my truck I'd put a fuel pressure gauge in either way. Cheap insurance that can save your expensive injection pump.

John

 

Thanks alot John, Ill check it out. I think the old man is wanting to go back to a gas so I may trade him my 98 1500 for his 12 valve ? we shall see

 

where is the over flow valve located?

 

if it was the ofv it should start up hard. does it smoke at all when trying to pull a hill. You might want to clean the prefilter screen in the fuel heater, its right next to the lift pump. the bottom should screw off. Check the boost line going to the bakc of the afc housing to make sure its not cracked. might also want to check the wastegate on the turbo and make sure its not hung up.

 

I had the plug, spring, and ball pop out of my OFV and the truck still idled and started fine. It had no power up top though. Of course that is an extreme case compared to an OFV that is just worn out but if the truck still started and idled OK like that then it should start no problem with a weak OFV. The first thing I'd do is unbolt the exhaust and check the wastegate, they're both easy to do and don't cost anything. After that I'd put a fuel pressure gauge on it (which really should be installed anyway) and see where that is at. If the OFV has never been done before, then I'd say that it is LONG overdue for one. I'd also clean out the pre-filter or seriously consider replacing it. There's a pretty good chance that the fuel heater isn't working anymore so you might as well remove it while you're down there. I removed mine and the truck has been starting fine in the teens and twenties here in NY, you live down in Texas so you should have no problems starting it without the fuel heater. It doesn't cost anything to remove and its just one less thing to go wrong.

John

 

No no smoke up hills just doesnt want to go up them anymore. I'M gonna check the screen and take of the exhaust and make sure the wastegate is still operating.

 

If its not smoking then its probably a lack of fuel but you never know.

John

 

How long since you replaced the fuel filter?

 

we did the filter not too long ago, so? I'm leaning towards something mechanical

 

My 96 had very low power when I got it . It turned out to be the fuel shutoff solonoid. The rubber boot was shot and allowed dirt inside and the valve wasn't opening all the way. I took it apart and cleaned the plunger and solonoid insides and power was up greatly.
Check to see if yours is pulling up all the way. Just one more thing to eliminate.