Stalling out at highway speed

[pistolnut]

I've recently gotten the mostly stock '67 back on the road after about 3 years of limited ranch use. This truck has always been exceptionally reliable, and would happily do nearly 70 back when I was driving it regularly on the road (I seldom drove it that fast, but it would do it).

This former fire truck is stock except for a civvy distributor and ignition on 12V, and an electric fuel pump. I just replaced the plugs, plug wires, battery, fuel filters, and installed carb kit.

The truck runs good except for when driving on the highway (50-55) after a few miles it will start to stumble and stall out. I end up having to reduce throttle to get it to run smoothly, until finally a few miles later I'm down to 25-30. After cooling off, the truck runs well again. I've changed to another (used) coil, thinking that it might be getting hot and working poorly. I'm wondering what else could be the problem: vapor lock?, condensor?, Any thoughts?

[Barrman]

Clint,
Glad you got the fuel pump and lights working at the same time. I am thinking fuel filter or fuel sock in the tank. Remember when my truck died a few years ago as we were in convoy to the MV ranch? I would suggest changing any filter you have and back blowing into the tank from right at the tank.

[maskale]

Sounds like a fuel issue. Check your vent on the tank. If its partially clogged it will do what your saying. During cool down the tank looses its vacuum and you are good to go again for a while. Also check your filters.

[pistolnut]

Thanks for the suggestions, I think it's a fuel issue too. I checked the vent that runs from the filler neck to the air cleaner and it is clear. I'll try blowing out the fuel line soon.

[pistolnut]

I think I finally got this whipped. The short rubber fuel line after my electric fuel pump had a bend in it. The hose was badly softening and deteriorating(ethanol?). I think it was collapsing when temps under the truck came up after driving a bit. I replaced the hose today and its running great so far, even on the run where it had been having trouble.

[maskale]

thats good.

would be good to go ahead and replace the rest of your rubber hoses. If you are concerned with temps then go for fuel hose with the SAE 30R7 rating.

[MJCougler]

OK, I'll ask. What is the SAE 30R7 rating. Is it an ethanol rating?

[osut362]

SAE 30R7 hose is 50 psi F.I. hose. It is more ethanol resistant, not ethanol proof..........al

[maskale]

Sorry, but the 30R7 is NOT for fuel injected supply pressure. It can be used for the return line. 30R7 is a low pressure line. I recommended it in this case because the OP made a concern about temp. The 30R7 has a higher temp rating then the more common 30R6 hose. 30R7 cost about $2 per foot, 30R9 is better all around $4 per foot.

30R6

■Specially designed for gas,oil, diesel, and other fuels
■Resists temperatures up to 212°F (100°C)
■Minimum Burst 175 PSI (1.2MPa)
■meets and exceeds SAE J30R6 specifications
■ChemigumTM tube compound for outstanding resistance to petroleum based fuels
■Two Spiral Polyester reinforcement
■ChemivicTM cover compound for exceptional abrasion resistance and exposure to



30R7

■Recommended for clamped hose application on all fuel systems
■Nitrile-based tube provides exceptional resistance to a variety of fuel systems
■Cover compound provides exceptional oil, heat, ozone and weathering resistance
■Temperature Range -30°F to 257°F (-35°C to +125°C)
■Nitrile-based ChemigumTM tube compound
■Two-spiral polyester reinforcement
■CSM (Chlorosulfonated Polyethlylene) cover compound



30R9 is for fuel injection

■Hose meets the most demanding industry standards
■Compatibile with gasoline, ethanol extended fuels, diesel and biodiesel fuels
■Conforms to CARB requirements set forth in 13CCR section 2754
■Exceptionally flexible for easy routing
■FKM fluoroelastomer rubber tube has low permeation and chemical resistance
■Single braid aramid yarn reinforcement provides exceptional dimensional stability in high temp environments
■CSM (Chloro-sulfonated polyethylene) cover compound resists wide range of fuels, oils, lubricants, including Biodiesel fuels. Exceptional heat, ozone and weather resistance
■Temperature Range -30°F to +257°F (-35°C to +135°C)


http://www.goodyearep.com/ProductLis...?folderid=1036

[osut362]

F.I. return hose. That is correct and I stand corrected.......al