First post.

As the title says, I have a 1991 F150 4.9L M5OD Single Cab. I bought her from an OLDER gentleman that stored her in a storage unit since 2003. To get her road worthy he replaced the starter, battery, fuel pump, exhaust, and water pump. I drive the truck at least once a week, sometimes more - for at least 30 minutes to an hour. (I have a new cummins Titan XD as a daily)

I changed the oil, 2 times with the recommended motorcraft oil and filter, brand new copper champions and wires, new air filter, TPS, and a new Ignition actuator (I broke the piece off mine that seems to break on a lot of these and the truck wouldn't shut off - Good thing its a manual!

After running for about 30 seconds it begins a rough idle that is noticeable (vibration/shake about every 2 seconds) - I really do not know what it could be and turned to replacing the vacuum lines for good measure but I guess I ordered 50ft of the wrong 5/32" ID rubber line. It looks like most the lines are slightly bigger on some ends and this line will not go over those Y splits plastic pieces.

Any ideas? Recommendations?

She does drive just fine. No issues - Maybe bearing in tranny (noise while in N?) is on its way out, but I will rebuild it in a few months after i'm done moving and settled into the new house. Shifts just fine, and clutch seems to be fine - if anything its touchier than one would guess.

Thanks!

 

Additionally, yes it sat in a storage unit for over 15 years and fires right up and drives just fine.

Yes the other fluids are all 15++ years old.

It either has 53k or 153k miles. I would believe either.

 

take the plastic fittings down to the part store and use it as a guide to find the proper size hose, you can usually find plastic fittings to replace any that are bad or something that will work. When the engine is running use carb cleaner to spray around the engine to check for vacuum leaks making sure to spray around where the throttle body meets the intake, a lot of those gaskets fail and will cause issues,they cost about 2 bucks and take nothing to replace. That is where I would start.

 

I have visually looked around most all of the motor - granted some vacuum lines go into areas I would not have put them, but from the naked eye it seems correct and in place. I have heard about checking this way but have not ever done it using that method before. The fact that it rides and drives just fine is the only reason it doesn't both me but I plan on keep and restoring this truck as she deserves the justice.

 

2 things to address..

1st Pull codes.
2nd I dont think anyone here would recommend Champion spark plugs in a truck or car, but they do run them in lawn, atv's.

Need to find out if the wires are crossfiring. It does sound like maybe crossfiring.

Pop the hood at night and look for arcing.

I'm tired...can't think of anything else.

Check for codes.

 

https://www.ford-trucks.com/forums/1...t-project.html

 

As stated above, codes are good start. Fuel pressure is high on the list, in general.

Mityvac is good for vacuum issues.

Five speed behind a big six makes a really cool truck. There are some differences for the six and eight cylinder trucks. So don't assume everything you see applies to the six.

 

Ah, I put recommended in these. Cannot remember the brand - Put the champions in the Jeep they other day and got confused.. Disregard this lol.

 

Yeah its quite the thing as I'm a diesel man, I have gained a certain love for this thing since purchase for sure.

All I needed was the size as I found out I needed the 7/32 and 5/32 - it helped.

 

I didn't the wires, but I did check and there is no arcing. Thank you

 

 

codes, vaccum leaks

check egr valve with vaccum pump, might be sticking partial open

 

test for map sensor https://troubleshootmyvehicle.com/fo...e-map-sensor-1

to eliminate egr valve, pump a vaccum pump on valve while engine is running. apply and release vaccum while hitting egr valve with hammer to try and break free any loose carbon that may be holding valve open. work it open and closed 5-10 times and see if that solves your issue.

 

This helped when I had a similar issue

 

The noise in neutral could be a worn shifter bushing. The rebuild kit is in the $20 range and is readily available. I'd rather try that first then drop the tranny and start doing throwout bearings... but I am lazy