chicofuentes0224 Posted December 7, 2007 Share Posted December 7, 2007 Is it possible that the fuel pump gets enough pressure at idle, but driving it's not pushing out enough fuel causing the truck to stutter and feel like it's putsin along. Link to comment Share on other sites More sharing options...
carnuck Posted December 7, 2007 Share Posted December 7, 2007 Possible, but other things may be affecting it. Using a fuel pressure gauge will tell you if that's what's happening. Could be something stuck in the regulator or clogged filter or clogged screen in the tank. A can of BG's 44K will usually clear up most of those symptoms, at least temporarily. Link to comment Share on other sites More sharing options...
chicofuentes0224 Posted December 7, 2007 Author Share Posted December 7, 2007 I hooked up a gauge to the valve on the rail. The PSI is on spec with the vaccum hose on and off but I only did it while it was idling. The fuel filter is new. The truck just runs like crap from 1700 rpm. So I either have to lightly tap the gas or gun it. It's an automatic by the way. It just feels like it's not getting enough gas. By the way what's that stuff you said and where do I get it? Link to comment Share on other sites More sharing options...
chicofuentes0224 Posted December 7, 2007 Author Share Posted December 7, 2007 You wanna know what's strange. If I drive a while and turn it off and turn it back on. It seems to run better. The more I do this the better it runs. Do you think it might be the CPS? Link to comment Share on other sites More sharing options...
Duner Posted December 7, 2007 Share Posted December 7, 2007 It might be an o2 sensor does the engine run better win get the revs over 3000-3500 if so you might change the o2 sensor to gain back the low end performance from idle to 3000. Link to comment Share on other sites More sharing options...
chicofuentes0224 Posted December 7, 2007 Author Share Posted December 7, 2007 The O2 sensor is new. But I thought it doesn't even kick in until the car is warm and this problem happens cold or hot. Link to comment Share on other sites More sharing options...
carnuck Posted December 8, 2007 Share Posted December 8, 2007 On the 87 to early '89s, there is a big electrical connector above the brake booster that gets corroded and messes up the signals to the computer (you can even get high revs on restart from it) Link to comment Share on other sites More sharing options...
McClare Posted December 8, 2007 Share Posted December 8, 2007 If it's freezing cold out you might have some water frozen in your lines. If that's the case try a bottle of gas line antifreeze. Link to comment Share on other sites More sharing options...
ejndssn Posted December 8, 2007 Share Posted December 8, 2007 how old is the EGR valve this can contribute to poor performance :brows: would not like for you to go on a witch hunt and start replacing parts you don't need yet. Link to comment Share on other sites More sharing options...
FxRacing282 Posted December 8, 2007 Share Posted December 8, 2007 :agree: you may have dirty injectors. or a dirty air filter. i would say get injector cleaner and clen them out real good and see what happens. BUT, before you do anything run your tank of gas to empty and fill her up somewhere different, quite possible you have bad gas. Link to comment Share on other sites More sharing options...
chicofuentes0224 Posted December 9, 2007 Author Share Posted December 9, 2007 you may have dirty injectors. or a dirty air filter. i would say get injector cleaner and clen them out real good and see what happens. BUT, before you do anything run your tank of gas to empty and fill her up somewhere different, quite possible you have bad gas. Not that, I tried that. Link to comment Share on other sites More sharing options...
chicofuentes0224 Posted January 17, 2008 Author Share Posted January 17, 2008 Well three months and some parts later I still have this problem. Here's the differnce though. I now notice that if I let the truck warm up for about 15 to 20 minutes I no longer have this problem or it's barely noticeable. New parts include: Fuel filter, plugs, wires, TPS, oxygen sensor, distributer cap, rotor, CPS, CTS, knock sensor, 19lb injectors. So here's what I'm thinkin. There is something in that engine bay that expands when it gets hot enough and therefore creates a tight seal not giving the stupid renix sensors mixed signals. So maybe an airleak somewhere? I though that maybe it was the bolts to the intake manifold but all those are all on tight nowand no change. I changed my ccv lines but oil still leaks from the new grommets leading me to believe that maybe this is causing the problem and the grommets expand (especially the one going from the back of the valve cover to the intake manifold) sealing off the air leaking and creating the necessary vaccum? Maybe? Next theory is that the piston rings are shot completely and because it is cold do not create the necessary compression untill they warm up completly and expand forming a tight seal with the cylinder walls? However compression tests show that all cylinders are good except #1 is a little lower. Of course, there is still the MAP sensor, EGR, MAT sensor that ned to be changed, but if these were faulty it would stutter all the time and not get any better as the temperature in the bay warms up. So kids, any ideas? PLEASE HELP ME!!!!! Link to comment Share on other sites More sharing options...
Pete M Posted January 17, 2008 Share Posted January 17, 2008 I've heard (but not yet tried for myself) that you can find some vacuum leaks by using a propane torch (without igniting the flame of course). The theory is that when the gas gets sucked into the leak, the engine will burn the propane and the idle speed will change slightly. Keep the gas on a low setting. Link to comment Share on other sites More sharing options...
chicofuentes0224 Posted January 17, 2008 Author Share Posted January 17, 2008 OK , now I gotta find a propane torch. Thank you sir. Any other suggestions? Link to comment Share on other sites More sharing options...
512tr Posted January 17, 2008 Share Posted January 17, 2008 To look for vacuum leaks, use START GAS, spray over potensial leak areas. If you have a leak, the idle rpm will increase. Link to comment Share on other sites More sharing options...
Pete M Posted January 18, 2008 Share Posted January 18, 2008 Same principle. :D Just be careful with all the highly flammable stuff. Link to comment Share on other sites More sharing options...
FxRacing282 Posted January 18, 2008 Share Posted January 18, 2008 it oculd possibly be a faulty heater in the O2 sensor. an O2 sensor needs to be like 1000F or something rediclous like that. just might not be heating up fast enough Link to comment Share on other sites More sharing options...
chicofuentes0224 Posted January 18, 2008 Author Share Posted January 18, 2008 FX are you talking about the O2 heater relay? Link to comment Share on other sites More sharing options...
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