Hello. My 87 Chevy (350 TBI, 4WD) is acting up. The idle is extremely low. When I come to a stop, the idle drops so low it nearly shuts off (sometimes it does). Then it lollops on me. No issues once I apply throttle. I recently replaced the fuel pump (Bosch) and serviced my K&N. The fuel filter is semi-new. The PCV looks good and I keep up with my maintenace precisely. Any ideas??? Vacuum hose? Electronic? Help.
Did this happen after you did the pump & tune up work.? The fuel filter is clean after the new parts, you might have to unplug the batt. Let the computer reset I beleve 3 min is good then reconnect. Retest (fuel filter inline is the right way just in case. "Flow" ) If that does not work the injectors or injector lines might need cleaning. This is assuming that all your hoses are good not sucking air or leaking. Mabey some eles can add some more info. I hope this helps
my 87 did the same thing after i replaced my pump come to find out they gave me one for a carb not TBI chevy put both out that year might want them look the one they gave up make sure its for TBI carb units dont put out enough pressure.its worth checking
lol that could be it too good point. the TBI does use more fuel pressure then a carb does. But most TBI fuel pumps are in the tank. So if it's on the block there and it only puts 5-1\2psi then it might be for a carb set up.
Good Point I Assumed His Was In The Tank.all My Tbi Cars The Block Is Sealed At The Factory You Cant Put A External On If You Wanted Too.so I Didnt Ask I Figured It Had To Be Electric.
Re I reset the computer...no luck. I also verified the new fuel pump was the correct one. So I'm back to square one. Any more ideas, guys? Thanks for the all the help so far. I'm sure it's something simple. Kris
One thing to try is leave the PCV hooked up pull it out of the valve cover take it for a drive see if it still does it.As a though Maybe the pcv or the pcv hose.How much miles on the motor does the motor seem to have a lot of blow bye? other than that can't think of any more right now. It's the small stuff some times that get you the most.
i'm surprised nobody said anything about spark....how are your plugs, wires, cap, rotor, and timing...check base timing and advance curve, also does that truck still have an EGR valve....could be stuck....that can cause a poor idle.
I had a problem with mine were it would not idle at all. But if you started it up and applied the gas then it would run. Come to find out it was the Idle Air Control Valve. It is located on the side of the throttle body. It controls your idle and they are known to go bad and your vehicle will idle really bad or will shut off like mine. So if it just does it when you are at idle it may be that. Once i put mine in it started right up and idled perfectly. Hope this was of some help to you.
Also know as throttle position sensor. Same thing happened to me on a '87. It would either idle real high or REAL low, almost die. Not expensive and very easy to change. Near the rear of the throttle body, 1 plub and a deep socket and your done. I also replaced the coolant temp. sensor at the same time, I thought it was that one when it was idling high. Both sensors about $50 total. I'd do the TPS first.
You may want to check the oxyger sensor for the lollops. That sound like what happen with me before but in a car not a truck. It would act like its not getting gas untill you reached a good speed. But even then it would do it a little.
