This is my first post here, and I have a 97 4x4 auto trans and just noticed that it will not go past about 2300 rpm when in gear. I can hold it in 2nd gear and that is all I get as well as in all other gears. I have done some reading on the forums already and am looking toward the overflow valve as the problem. I already replaced the fuel filter and that didnt change anything. Hopefully someone can point me in the right direction. Maybe school me on what and where the overflow valve is. THANKS, Chad Patten!

 

The overflow valve is a check valve used to control fuel pressure in the injector pump. It is incorporated into a banjo bolt located in the fuel return line where it attaches to the inj. pump. The location is high on the pump, toward the front, on the inner side (between the inj. pump and the engine). It's got a 3/4" hex and secures a hard fuel line to the pump.

To diagnose it properly you need a fuel pressure gauge, but as a "field diagnosis", with the engine "off", give your fuel primer button a few pushes, you should hear your overflow valve squeak with every push. If you don't hear a squeak, you have a problem, either in the valve itself, or somewhere in the supply circuit.

 

You need pressure and volume to make the truck run right , the valve is what makes pressure by restricking the flow back to the tank , thats if the pump is pumping enough volume- as they wear out they pump less volume - and then theres the lift pump also , thats why a lot of guys put fuel gauges on the later trucks becouse they had a weak lift pump and the truck can run on a dead lift pump but it shortens the life of the main pump so its very important to keep tabs on the lift pump with a fuel gauge.

 

If the truck isnt popping/missing, or white/blue smoking any, then all you need is a $125 Governor Spring kit . These trucks do govern out around 2400rpm stock, but with the governor spring kit, they pull hard all the way up to about 3000-3200rpm. Mine would only go to about 2400 in drive before, but after the governor spring kit,m when i still had the stock converter, it would pull to 2700. Then once you got to 3rd gear, and tghe converter locked, if i held it out of overdrive it would pull to about 3100rpm. www.tstproducts.com or www.piersdiesel.com both sell them for about $125. Installation is not to bad. More intimidating than anything. Good luck

Eric

 

A major part of your defueling as well

is your stock fuel plate. that is one ugly restrictive plate. A GSK and a fuel plate will wake up your truck as Eric said. Id do it if i was you!

As far as a plate change and what is right for you? just search and see.. But as a quick guide if you perfer to change out your plate

0 plate most agressive, most fuel at all positions (see my gallery for pics)
100 plate very agressive, yet still streetable, no defueling at top end ( again see gallery)
Banks plate.. Screwy looking, fuels hard at first, then gradually slows down, truck fuels hard till 2800 or so rpms.... in mine at least...

Tx

 

Is there any way to fix this problem with out much money? I did take notice this afternoon and it really blows white blueish smoke while I have it floored and it is just sitting there revving between 2000 and 2300. I called the previouis owner and he said that the mods it has are a modified valve body in the trans. He capped the egr system off. and he said that he had pulled the injection pump and had it "recalibrated." Is there a way to take apart the overflow valve and tweak on it?

Thanks, Chad

 

Sounds like you do have a fuel delivery problem then, or possibly timing... I would guess its either your lift pump or the O/F valve. Call Marty Thompkins for the overflow valve. I cant remember His #, but if Infidel sees this im sure he will chime in. I think i paid about $25+$7 shipping. Cheapest you will find, and a great guy. You CAN take the O/F valve apart, and try stretching the spring to like .500, but im not sure if thats a good idea or not.

Eric

 

Have you ever adjusted your plate? Like trying to slide your stock plate forward and accidently slid it the wrong way? I know when I did that with my stock plate it would never rev up high at all. Even with your stock plate you should be able to get it up to redline, (Not making power) but get it there. Just something easy to check before you start spending money trying to fix it.

 

I have never really touched the pump. Is messing around with the fuel plate relatively easy? The truck will go up past redline in neutral just fine. I need to find some good tech articles about tinkering with the pump like you are talking about.

 

Back to basics or as John Faughn mentioned about pressure & volume.

Have you changed the fuel filter? I got a load of something this summer and my filter gradually plugged to the point I could not get more than 2,000 rpm out of the beast. I have GSK so it will hit 3,200 rpm on an average day.

New filter and back to normal

 

I put on a new filter and it didn't help me at all

 

Chad..

this is a newbie tutorial that i have.. Please read it and i hope that it can help you. Do not be afraid to tweak with your plate. it is not hard at all, and it explains some of the stuff that you have read on here...

https://www.dieseltruckresource.com/...131#post806131

Thanks and hope it helps

Tx

 

I think I may be looking at a new lift pump. I pulled out the Overflow valve and it looked fine, I even stretched it out to .500, ran the truck and now It revs a little higher but now it just does the same thing at a little higher rpm. Is a lift pump hard to change? Also how do I install a fuel pressure guage and where do I install it?

 

Chad you really need to start right, get some guages first ,boost and pyro minimum. Next change your fuel plate and add a 3gsk spring kit and and afc spring kit and a BHAF so your engine can breathe and deal with the extra fuel from your mods. with my mods i will defuel at 2500rpm, need a 3k kit myself. I am able to get 34psi of boost and a real nice smooth torque pull all the way through the rpm's. before i added my #8 plate the truck was a big lug and you had to be careful getting on to the highway as it had no get up and go once in overdrive at 55mph.

 

Well... I think I learned a lot about my fuel system after yesterday. Someone advised me to go to a guy that was close to me to help me work on my truck. So I drive my truck in to his shop and the truck didn't leave with me. ITS STILL THERE! We first checked fuel pressure.. That was at 10 psi. Not high not low so we then checked my pump timing to see if it slipped. we got a reading of about 15* advanced... So that seemed okay also. put it all back to gether and went to start it up and I right on the first crank we hear this weird POP from the pump. It fired up but ran real rough for about 8 seconds then died. We check fuel pressure again and try to get it started. NOTHING. We decide to recheck the timeing and find chunks of metal in the #1 delivery valve where the dial indicator goes!***!!! I don't have the slightest clue how it happened! So Now my pump is at Rocky Mountain Fuel Injection and the Damages total about 1300 Bucks! This doesn't include the time that the guy that was helping me has in it. I don't know what to think. There is a collar on the grooved pin of the delivery valve, that collar was allthe way gone off the pin. Has anyone ever heard of such a thing? Since I am doing all this work, and I am already gonna be in major debt, I am doing the KDP a new lift pump, rebuilding my injectors, 3000GSK, #10 plate, and guages. Sorry this thing is sooo **** long, I guess it is my way of venting. I sure do know a lot about p7100's now and what they cost!!!!!