kevinde1
Member
- Joined
- Feb 26, 2017
- Posts
- 32
- Reaction score
- 0
- Location
- Oklahoma
- First Name
- kevin
- Truck Year
- 1987
- Truck Model
- R10
- Engine Size
- 5.7l
Hello guys I'm new to the forum but I've been visiting it regularly since I've bought this truck. I recently bought a 1987 SWB with 5.7l TBI. When I got the truck it had a surge that seemed to get better once it was warmed up. I thought no big deal its a good deal I'll figure it out (lol). Now for the meat and potatoes.
cleaned grounds
baseline timing @ 0 degrees this was not the case when I bought it.
new fuel pumps@14psi
New Filter
rebuilt throttle body
previous owner replaced all the sensors
EGR valve
TPS
IAC
CTS
knock sensor
map sensor
oxygen sensor
distributor
I have tested the TPS and MAP and distributor pick up coil and they are in range. EGR is clean and clear ports at the manifold. I'm pulling 21Hg in vacuum using a vacuum gage I checked for vacuum leaks all over the place and doesn't seem to be one. I've reset the IAC and reset the computer.
Here's what is happening when I put a hand held vacuum pump on the MAP sensor and put 21Hg at the sensor it kills the engine. If I use a can of carb cleaner I can keep it running. It starts to cut out at 17Hg and the MAP will cut the fuel off and kill the engine. So now I see why its surging the MAP reads 21Hg kills the engine, the engine starts to shut off then there's low vacuum at the MAP and then engine picks back up and starts the cycle all over again. If I put a hand help vacuum pump at the MAP and put 15Hg on it truck runs smooth but a little rich but increase that to 21Hg where it should be, at 17Hg it starts to die. Anybody know what would cause this? this leads me to the ignition control module or the ECM does anybody know how to test ICM? Anybody have any Ideas? Another thing I'm going to check today is the thermostat with the temperature gun its reading 145F at the neck of the radiator hose. Thank You for your responses
cleaned grounds
baseline timing @ 0 degrees this was not the case when I bought it.
new fuel pumps@14psi
New Filter
rebuilt throttle body
previous owner replaced all the sensors
EGR valve
TPS
IAC
CTS
knock sensor
map sensor
oxygen sensor
distributor
I have tested the TPS and MAP and distributor pick up coil and they are in range. EGR is clean and clear ports at the manifold. I'm pulling 21Hg in vacuum using a vacuum gage I checked for vacuum leaks all over the place and doesn't seem to be one. I've reset the IAC and reset the computer.
Here's what is happening when I put a hand held vacuum pump on the MAP sensor and put 21Hg at the sensor it kills the engine. If I use a can of carb cleaner I can keep it running. It starts to cut out at 17Hg and the MAP will cut the fuel off and kill the engine. So now I see why its surging the MAP reads 21Hg kills the engine, the engine starts to shut off then there's low vacuum at the MAP and then engine picks back up and starts the cycle all over again. If I put a hand help vacuum pump at the MAP and put 15Hg on it truck runs smooth but a little rich but increase that to 21Hg where it should be, at 17Hg it starts to die. Anybody know what would cause this? this leads me to the ignition control module or the ECM does anybody know how to test ICM? Anybody have any Ideas? Another thing I'm going to check today is the thermostat with the temperature gun its reading 145F at the neck of the radiator hose. Thank You for your responses
Last edited: