Idle issues

[jellybelly]

So I just bought my Grandfather in laws all original 1985 F250.

A sweet ride with 37,000 original miles...with original tires. Definitely going to buy some new ones.

So I changed the air and oil filters. Changed the oil. Topped up radiator.

I can't find the fuel filter but I will keep looking...suggestions would be great...have read everything from near the DS door, need to get a flashlight and try to follow the fuel line I guess.

Put some gas with some sea foam in there and started it up.

Idles pretty good for a little bit and then acts like it wants to die unless I give it a little gas.

Paw paw said it has done that for quite a while. He would drive it and it would cut out at stop lights. He said he took it to some mechanics and they couldn't figure out what was going on.

Before looking at idle screws I was just wanting some input into what might also be causing the problem. Any ideas?

 

[Fellro]

Could be as simple as being varnished up and needs some cleaner run through it and fresh gas. You don't mention what you have for a motor, but if carbed, the fuel filter should be screwed in to the front of it. If it truly has that low of miles, it likely needs a fuel system cleaning.

 

[Beach66Bum]

looks like it has the 5.8 (351) in it by the exhaust pipes, the 5.8's had that dual tip exit. Should be carbed ? thinking that 1986 was the year fuel injection came in. Like Roger said, the fuel system will need a go through, and the carb checked and adjusted (if it is carbed)

 

[5.0Flareside]

looks like it has the 5.8 (351) in it by the exhaust pipes, the 5.8's had that dual tip exit. Should be carbed ? thinking that 1986 was the year fuel injection came in. Like Roger said, the fuel system will need a go through, and the carb checked and adjusted (if it is carbed)

85 302's some were carb'd some EFI, 86 all 5.0 were EFI.
87 300 I6 were all fuel injected
88 351W and 460's were swapped to fuel injection


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[Beach66Bum]

Thanks Chris!

oh, I was on You Tube and happened to come across a vid of your's from 2010, your cammed '88. (I recognized your old user name)

 

[5.0Flareside]

Lol.. Yeah I miss that damn truck...


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[jellybelly]

Carb

Sorry. It is a 351 5.8 4b.

I was reading somewhere that I probably need to adjust the idle. ,it idles fine until u put your foot on the gas. Then it goes to low idle. And it is low idling way too low.

I'll let u know if I if I find the fuel filter. Couldn't see it near the carb.


Hoping the sea foam will clear out some of the gunk.

 

[Beach66Bum]

By your description, that sounds like you're talking about when you first start your truck and it's on cold idle cam setting. Then when it warms up and you press the gas pedal it drops to the warm idle cam notch. Yes, you need to adjust both the choke setting cam and the idle screw. They work together.

 

[primetime]

The fuel filter is in the float bowl on the carb where the fuel line goes in. There is the fitting on the fuel line which I think is a 5/8, and a fitting directly above that that screws directly into the float bowl which should be a 1 inch if I remember right. Hold the big fitting while you loosen the line, then remove the big fitting and the filter is in there.

By the way, nice truck.

 

[jellybelly]

got something figured out.

The fuel filter is in the float bowl on the carb where the fuel line goes in. There is the fitting on the fuel line which I think is a 5/8, and a fitting directly above that that screws directly into the float bowl which should be a 1 inch if I remember right. Hold the big fitting while you loosen the line, then remove the big fitting and the filter is in there.

By the way, nice truck.

Thanks for that fuel filter location primetime I'll get onto that...



So I got the truck out and had a quick look at it again.

Here's what it is/was doing

Starts perfect. As soon as you push gas pedal it dies.

So i adjusted the idle so it doesn't do that.

However when it gets put into gear it low idles and dies.

So I thinking a vacuum problem. If I adjust idle up more it won't die but when in park it will race at probably 4000rpm (no tach so that's a guess) and when in gear it will idle at probably 800rpm.

What do you guys think?

And how do I go about checking for vacuum leak on the truck?

 

[jellybelly]

Neighbor came over and pointed out fuel filter location in 2seconds...feel like an idiot. I'm used to working on vintage Goldwings.

He also pointed out that the diaphragm in PVC and some other valve thing might be my problem.

 

[jellybelly]

Egr valve maybe.

 

[jellybelly]

Problem solved. I had a barb that had no hose. Blocked it off and problem solved

 

[primetime]

Glad you got it sorted out.