I know this is for tractor talk but didn't see any other place to talk about my F150. It is a 1990 with a 300 cid fuel injected 6 cylinder. It runs rough/cuts out at times when cruising but under acceleration it runs great. Starts great plenty of power no back firing, idles great. Does any one know what may be wrong with it? I thought possibly a vacum leak but it's direct fuel injection so I would think that rules out a vacum leak.
- Thread starter John B.
- Start date
Anonymous-0
Well-known Member
moisture in the tank? This is the right weather for it, especially if you don't either keep it full or run it clear empty.
Try this forum:
http://www.ford-trucks.com/forums/forum28/
Should get some good and quick answers there.
DAve
Try this forum:
http://www.ford-trucks.com/forums/forum28/
Should get some good and quick answers there.
DAve
Anonymous-0
Well-known Member
May want to go through and clean/check all grounds and connections. You need good voltage to make everything tick right and a bad connection could restrict power. Higher RPM's would boost a couple of volts and make things right.
Just a thought.
Dave
Just a thought.
Dave
Anonymous-0
Well-known Member
Check the fuel pressure regulator. The back side of the diaphragm is the vacuum system. A broken diaphragm puts fuel into the vacuum system and can make it run rich. I had an '86 with the 302 V-8 and it had only the single fuel filter in the frame rail. So when the vacuum diaphragm split the fuel pump could hold up injector rail pressure, but it put so much fuel to the hydraulic system that it hydrauliced the engine. Essentially it cost me the truck after a local shop caught it on fire trying to figure out why the cylinders were getting so much liquid gasoline (and the gas that got to the crankcase didn't do the bearings any good either).
Gerald J.
Gerald J.
onefarmer
Well-known Member
- Location
- 6735 S Lowell Rd, St Johns, Mi 48879
O2 sensor??
Anonymous-0
Well-known Member
And don't overlook the ignition module if applicable, I think they were a recall item.
Of course if the ignition switch is coming loose from the column or falling apart that will do it too.
Of course if the ignition switch is coming loose from the column or falling apart that will do it too.
Anonymous-0
Well-known Member
It could very well be a vacum leak, there is a line to the MAP sensor as well as a few others.
I would recommend buying the Haynes repair manual, you can test all the sensors with a simple OHM meter rather than doing a trial / error type of attack.
I would recommend buying the Haynes repair manual, you can test all the sensors with a simple OHM meter rather than doing a trial / error type of attack.
Anonymous-0
Well-known Member
my '88 ford truck did the same thing. cruising speed it ran rough, fine under acceleration. service manager at ford garage rode along. we stopped and he got out and pulled the vacuum line off of the EGR valve. appartently this disables it. anyway it ran fine when we started off again . stopped again,re-connected, back to running rough. you my try this same approach to rule out EGR. The EGr valve is located at the top rear of the engine. they are pricey.
cornfarmer
Member
Had this same problem with my '95 F150 with the 300-6 cylinder-first tried egr valve trick without luck. Played around for a couple of months with all the other tricks you see posted here. Finally replaced the injectors and it ran like new. Truck had about 220,000 miles on it at the time.
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