1989 Eliminator Posted July 14, 2014 Author Posted July 14, 2014 I really do not think it is a fuel issue. But I am installing a fuel pressure gauge on my fuel rail sometime this week to see what my actually readings are. I also am trying to get ahold of a vacuum pressure gauge so I can also get values for vacuum at idle. By the way.... 100 post mark! :jump: :typing:
1989 Eliminator Posted July 15, 2014 Author Posted July 15, 2014 After doing all that I have done, after warming up the idle is fairly steady. It varies a little still but not as bad after a cold start. After a cold start the idle hunts a lot and wants to stall.
54bobby Posted July 15, 2014 Posted July 15, 2014 do you have an exhaust mani leak? my truck does the same thing but runs smooth once warm. i am attributing that to the mani expanding and somewhat closing the leek.
1989 Eliminator Posted July 15, 2014 Author Posted July 15, 2014 I cannot hear a leak and I recently had a crack welded on the ext mani. Obviously replaced the gasket and the bolts are all new and tight
1989 Eliminator Posted July 20, 2014 Author Posted July 20, 2014 Okay folks. Finally got a hold of a vacuum gauge. At idle I am reading between 16-20 Hg. This fluctuation I think is mainly due to the idle jumping around. But when the idle was "good" and not stumbling in the low rpms, the vacuum was 20 Hg. I wanted to give you guys a gas pressure reading too but I bought the wrong fitting.... Ill have the reading sometime this week!
1989 Eliminator Posted July 25, 2014 Author Posted July 25, 2014 All righty. Back with results. Sorry for the wait. Gas pressure is 31 with vacuum and 40 without vacuum which is good. I also have 20 hg of vacuum. So good numbers. My idle seems to be a lot better for some reason. I didnt much after all my electrical work and it kinda just went away. Id say the idle is still a little low but ill take a video and post it later!
cruiser54 Posted July 25, 2014 Posted July 25, 2014 All righty. Back with results. Sorry for the wait. Gas pressure is 31 with vacuum and 40 without vacuum which is good. I also have 20 hg of vacuum. So good numbers. My idle seems to be a lot better for some reason. I didnt much after all my electrical work and it kinda just went away. Id say the idle is still a little low but ill take a video and post it later! I'm assuming you cleaned the throttle body, adjusted your TPS on the engine side, and tightened up your intake manifold bolts? Checked your O2 sensor yet?
1989 Eliminator Posted July 25, 2014 Author Posted July 25, 2014 This has been a very long thread post haha Yes I have a new O2 and the TPS is adjusted and the throttle body is clean. All new manifold bolts as well.
1989 Eliminator Posted July 29, 2014 Author Posted July 29, 2014 So my fuel pressure when running is 32 and when i shut the truck off it goes to 39. Then after 35 minutes the pressure goes to zero. I know the pressure should hold for at least an hour so its possible i have leaking fuel injector(s). I might take them off and ultrasonically clean them at my work and see what that does
cruiser54 Posted July 29, 2014 Posted July 29, 2014 So my fuel pressure when running is 32 and when i shut the truck off it goes to 39. Then after 35 minutes the pressure goes to zero. I know the pressure should hold for at least an hour so its possible i have leaking fuel injector(s). I might take them off and ultrasonically clean them at my work and see what that does Ditch the stock injectors and get some 0 280 155 746 injectors from a volvo. Ebay even.
1989 Eliminator Posted July 29, 2014 Author Posted July 29, 2014 Really? Hm. I never heard about the volvos. I also thought the neon 703's were the way to go
1989 Eliminator Posted July 29, 2014 Author Posted July 29, 2014 man at $75 each thats kinda pricey. I looked on rock auto
cruiser54 Posted July 29, 2014 Posted July 29, 2014 man at $75 each thats kinda pricey. I looked on rock auto Wrong place to look. They're available on ebay. Also, Programbo and another guy sell them for about $100 per set refurbished on Cherokee Forum.
1989 Eliminator Posted July 29, 2014 Author Posted July 29, 2014 Perfect! I'm going to try a buy a dirty set from Programbo and then clean them myself. Hopefully this will make a difference!
1989 Eliminator Posted August 5, 2014 Author Posted August 5, 2014 Okay! Ultrasonic cleaned volvo 746 fuel injectors installed and now shes running a bit smoother! Good news. Better throttle response and smoother power through the rpms. I can still feel the mis sometimes though. The fuel gauge seems to fluctuate 2 psi or so and when the pressure drops so does the rpms. Maybe fuel pressure regulator?
1989 Eliminator Posted August 5, 2014 Author Posted August 5, 2014 Well I can't exactly check while I'm driving since the gauge is in the engine compartment but when I increased throttle via throttle body the fuel pressure increased from the 31psi at idle to around 35 psi. Then pressure stayed there as I held the throttle steady but there was still slight movement by 1 psi. There is more movement at idle.
cruiser54 Posted August 5, 2014 Posted August 5, 2014 Well I can't exactly check while I'm driving since the gauge is in the engine compartment but when I increased throttle via throttle body the fuel pressure increased from the 31psi at idle to around 35 psi. Then pressure stayed there as I held the throttle steady but there was still slight movement by 1 psi. There is more movement at idle. That's okay. Does it go to 39 when you pull the vac hose off the fuel pressure regulator though?
1989 Eliminator Posted August 5, 2014 Author Posted August 5, 2014 Yes the pressure does shoot to 40 psi when the vac line is disconnected
cruiser54 Posted August 5, 2014 Posted August 5, 2014 Yes the pressure does shoot to 40 psi when the vac line is disconnected That's all good then.
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