I have a 1993 isuzu spacecab with 310,000 miles

SOURCE: won't start-1989 isuzu spacecab-pickup-2.6

Did you sync up the engine properly when you reinstalled the timing belt/chain? It is possible to be on the marks and be 180 degrees off. Align the timing mark on the crankshaft then check the rotor position.If it doesn't point to number one wire terminal position roll the engine over until the crank lines up to the timing mark again. The distributer needs to be pointing the wire terminal that goes to number cylinder.Any other position is unacceptable and you can't simply turn the distributer to number one either You need to retime the crankshaft to the camshft making sure that the distrubitor points to number one and both valves for number one cylinder are completely closed.

Richard Lilja

• 401 Answers
• Posted on Nov 30, 2008

SOURCE: colt idle problem.

Most likely you have a bad Idle motor which is a small motor mounted on the intake manifold. If the motor can run better with your foot on the gas but dies if removed then it is probably this. This motor is controlled by the OBDII computer which gets it's control signal from the temp sensor which is located either on the radiator or engine block (which could also be bad), if the electric fan (if equipped) turns on then this is not the problem part, but the idle motor is. Another possibility is that you have some bad /cracked vacuum hoses which should be checked for first, before replacing the idle motor.

Dennis Mulford

• 1055 Answers
• Posted on Mar 05, 2009

SOURCE: f150 floods when cold, runs sluggish when warm

at that many miles its do a timing set

SOURCE: Engine stalls

sounds like one of a couple things could be causing you problems first would be the fuel pump may be wearing out. these are a mechanical pump and should be producing over 35psi at the injection pump if you have a way to put a gauge on it you could check this under full throttle is when you want to watch it though. fuel gauges are quite inexpensive and are handy to have in the truck anyway. another thing i have seen cause this is the check valve on the discharge of the pump there is a spring and ball in the return line banjo fitting that holds the fuel pressure at a constant 35 psi when that gets weak it allows more fuel to return to the tank which will let it run at lower rpm's but not under full load. hope this helps

SOURCE: rough idle after warm up

I'd take a look at the temp sender...the engines computer may be "thinking" the engine is still cold when it's not. That would cause it run rich (and rough) after it's warmed up. Generally the sender can be tested with an ordinary volt/ohmeter but you will need the specifications available in most inexpensive manuals. As with any complicated electronics system, I can only give you my best guess, without the luxury of doing any hands-on testing myself.
Good Luck!!