i have a 1997 6.5 gmc 2500 that only starts when it wants to.sometimes hot sometimes cold,have had it to chevrolet, there answer was too change fuel inj pump this truck has only 67,000 miles on it and use to sit for 6 months during the winter , does anyone have any ideas on what could be wrong with the truck i do not want too change fuel inj pump unless i am sure it is problem or does anyone know a reliable shop in lower catskills ny my knowledge of diesels is limited and any help would be gratly apprecciated ps once it wont start if you let it sit for 20 or 30 minutes it usually starts
I currently own a 97 GMC 2500 as well and, throughout its history, it has had 3 supposed 'fuel injection pump failures' Thankfully they were all on warranty. But lately it has started to act up again (surging, etc.) And I have read that often times its not the injection pump that is the problem...Its a think called a PMD (Basically the electronic module that controls the mechanical fuel pump) This often fails because of heat coming from the engine... (Fuel is meant to keep it cool but it is oftentimes not enough) I have heard that a failing PMD will usually cause hard starts as well (Your problem) You can get better info from the Diesel Power mag But if and when you go to a shop to check out if it is the PMD that is the problem I would suggest to spend the $500 and get a new PMD as well as a, what they call, a PMD isolator kit Once installed you should have absolutely no problems with hard starting or surging (Unless of course it is a faulty fuel pump (Highly unlikely ) but they run up in price of around $5000 (Warranty invoice)) Hope it helps
I have a 94 6.5. Had similar problem, checked everything, finally ended up changing out the oil pressure switch. The oil pressure switch controls the fuel lift pump. It may show oil pressure, but isn't activating the lift pump and your injector pump is trying to pull the fuel. Really hard on the injector pump.
i have a 1996 GMC 6.5 and i have the same exact problem as 71newlands has.Does anyone have any solution on how i can fix this? thanks a lot
-helloi see you have pretty much fixed your problem by changing the oil pressure switch..can you by any chance tell me where in a 1996 GMC it is located? so that i can change it. thanks
The oil preasure switch is in the valve gally close to the fire wall. you have to clime up on the engine and use a flash light to see it. I re wired my lift pump to run when the key is on instead of replacing the swich. (Gauge works). The hard start thing may be this or the PMD.(pump mounted driver) I had my GMC to the shop and same thing. They told me it needs a pump! I put up with it for mounths because when it would not start i would let it sit then try it again and it would fire rite up! Hot or cold it dident seem to matter. One day me and the wife were at the mall and we came out and tried to start it and it just cranked! No fire! WTF! Cold as a wiches tit I crawed under the hood and by chance I left the key on. I wiggleg the bat leads and herd a loud "click" I told my wife to try it and it fired up.
I was touching the pasenger side bat leads wile she started the truck. I burnt the crap out of my fingerstouching the poss lead! Turns out the bolt was tight holding the two leads to the pos termanal but the commection was intermitently high resistance. I looked in to it and found the computer runs off this side and the voltage was low to it. My lights, fan radio. All worked fine but the computer wasent getting the voltage it needed to turn on my Fuel cut soleniod!!!!! That was the CLICK i herd when wiggling the wires. I replaced one PMD on my truck. It was burnt out. Never a pump 200,000 miles! and I remote located the PMD. That is a must. The oil swich is a *** to get to to remove it but with the right scocket it can be done. Listen for a noise when you first turn on your key (not cranking) just in the on postion. It sounds like a small time bomb under the drivers seat. it stopps in just a few seconds. If you hear it go under the hood and crack open the "T" bleader valve on the top front of your engine, Just next to your oil fill. then turn on key, if fuel starts to be seen under the truck. I would say your OPS is good and lift pump.