so my truck has had a rough idle for the last couple months ( i think it is a dirty injector), but if i runs it for 30 mins or run it really hard then turn it off and back on it sounds like a tractor when i give it gas, almost like it is running on 4 cylinders. also it will idle even more rough than usual. would this be a fuel pump problem? if i let the truck sit for about 10 mins it will start up fine.

 

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Year, truck, engine, trans info needed. Have you pulled codes? Checked fuel pressure? Is it too much EGR?

 

1993 f150, 4.9l m5r2 trans, it seems like a fuel pump problem but i want to hear some other opinions. i haven't checked fuel pressure yet. codes 522 and 558 came up. one of which is something to do with a solenoid check failure i think. that might be causing the rough idle situation, but it could also be caused by the fact that the PO removed the vacuum canister and plugged the lines going to it. it always has a slight misfire even at higher rpms. but only after i run it for a while and let it sit for 10-20 mins will it be a very extreme rough idle.

 

Sounds like the emissions systems have been "modified". You need to get a handle on any vacuum leaks first.

 

Is the EGR system still in place?

 

as far as i can tell yes, except the vacuum canister. what kind of effect would the canister being removed have on the engine?

 

None....

The vacuum canister is a reservoir to supply vacuum when the engine is under load/low vacuum conditions.


You need to check the fuel pressure when the engine is running correctly and then again when the chugging/missing occurs.