I posted a question the other day about my truck. It is a 1990 Ford F250 with the 4.9L straight 6. When I turned it on, it would shake violently and cut off. I could make it drive by giving it a lot of gas, but when it drives, it was shaking very bad, the idle was random, and it would cut off at red lights. The shaking was worse at low speed. Very noticeable loss of power. I did a few more things to it since I asked last time and nothing has changed. Here are the things I have already done. Changed spark plugs and wires, distributor cap and rotor, changed coolant temperature sensor, cleaned IAT sensor, replaced the idle air control unit, replaced 2 vacuum lines that were dry rotted, cleaned throttle body, replaced throttle body gasket (had a leak).
I have done all of the above and it has not changed at all. There is a hissing noise when it is running, so my guess is that I have missed a vacuum leak somewhere, but it will not stay running long enough to check. I need some advise. Thanks.
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If it is flooding,pull the vacuum line off of the fuel pressure regulator DO NOT start the engine just turn to run not start see if fuel comes out the top of the regulator if yes replace it there's not to be any fuel coming out of the regulator at all .IF this does not fix your problem it's the EGO valve not closing off causing and vacuum leak change the EGO valve be safe my friend
Remove your IDLE AIR CONTROL VALVE, and clean out the passageways UNDERNEATH IT. Use SEAFOAM or power tune from mercury boat store. Re-clean your IAC valve as well. These engines had a few issues, but nothing too serious. Remove and check your spark plugs to watch for unusual coloration. You MIGHT have a bad FUEL PRESSURE REGULATOR. It's EASY to diagnose. Just remove the vacuum to it, and see if fuel spurts out. If it DOES, then it's BAD!!! Check the hoses from your PCV valve They usually rot out after five years. Have someone hold the engine rev's up a little to keep it running, then look for your vacuum leak. Two person job. Youwasted your money on new wires, the original usually last for the life of the car. Once done, switch over to BOSCh Fusion plugs. They simply fire more fuel more completely by catalytic action. E-amil me back with your results. GOOD LUCK!!
You need to get a hold of the vacuum lines for this engine and then slowly check each and everyone until you find the ones causing the trouble it still sounds like a vacuum issue
fire/insurance.