Loss of power @ 40-50 MPH under load (1 Viewer)

[Northbound]

I have the exact same issue with my 45 and it's brutal. It's a 77 2f with an aftermarket weber and I'm thinking timing or fuel starvation. That engine never heats up unless I block 50% of the grill with cardboard. It's winter in and it gets cold, but I can run all day with nothing obstructed and the mechanical gauge won't move. Highest I've ever gotten it to is 160 with the radiator 50% blocked.

I hope I can get it sorted it's so bad I won't even drive it.

 

[thebigredrocker]

It dies when braking.

Vacuum leak? Maybe clamp, kink or plug your brake booster hose and see what happens

Vapor locked fuel tank?

 

[Nottajeep]

Vacuum leak? Maybe clamp, kink or plug your brake booster hose and see what happens

Vapor locked fuel tank?

One more thing I tried is driving with gas cap loose

 

[Pin_Head]

It dies when braking. Tends to not respond to throttle and the spits and sputters.

Acceleration is going strong up to 50mph and then just stutters and kind of bucks forward and backwards.

Seems like electric would act up at slower speeds going over bumps also?

It sounds like it is running out of gas. The volume of gas the pump puts out is important too. It should put out about a cup of gas in 15 seconds of cranking with the coil wire pulled. If not blow out all the lines with compressed air and try again. Do you have the pump connected to the return line? That would do it too.


Dying when braking is a different issue. bump up the idle speed a little bit.

 

[lcwizard]

I have the exact same issue with my 45 and it's brutal. It's a 77 2f with an aftermarket weber and I'm thinking timing or fuel starvation. That engine never heats up unless I block 50% of the grill with cardboard. It's winter in and it gets cold, but I can run all day with nothing obstructed and the mechanical gauge won't move. Highest I've ever gotten it to is 160 with the radiator 50% blocked.

I hope I can get it sorted it's so bad I won't even drive it.

I've had Weber issues with trucks in warm weather and I could always cure it with an electric fuel pump and an adjustable regulator.
I use a regulator with a built in return mounted to the firewall as close to the carb as possible. this effectively shortens the feed line
to the carb. The pressure side runs from the pump to the adj. regulator. It splits internally with an output to the tank and one to the carb.
It virtually eliminates any possibility of cavitation or vapor lock in the system. I use a high flow pump like a walbro. If you ever go fuel injection
you'll already have the pump. Some regulators have a 1/8 npt port for a gauge so you can dial in the pressure. If not I would add an inline fitting to support a gauge.
Mr gasket makes a pretty inexpensive one that looks suspiciously like the doubly priced Holley

Mr. Gasket Fuel Pressure Regulators 2015

The Walbro style pumpe were used on many Ford trucks with dual tanks. There are a lot of brands and prices. I've run this cheaper brand on a truck for over 8 years then had an expensive replacement fail in two. Parts are hit and miss anymore so if just for testing pruposes I'll buy the cheaper. If it works then replace it when or if it fails

http://www.autozone.com/fuel-systems/fuel-pump/premium-fuel-fuel-pump/563488_478956_6210

 

[kruisinkid]

It might be time to empty, pull, and flush your gas tank. Its a pain but i had to flush mine out twice to get it clean. Pickup was getting blocked when there was less than half a tank of gas in it.

 

[Nottajeep]

Letting some techron fuel system cleaner soak in the tank and lines while I'm on travel this week.

I'll check the line from pump to carb again. Pretty sure the fuel is not going in the banjo bolt.

Any harm in blowing compressed air through the hard line towards the tank with the tank line still connected?

Are the rubber lines coming out of the the tank to hard lines 3/8"?

If I replace the tank, go OEM or change to poly tank?

 

[kruisinkid]

If you have a return line the air pressure will go that way. Maybe take off the gas cap? You dont want to pressureize the tank.

Me, i would blow toward the pump from the tank and sacrifce a cheapo filter.

Rubber lines should be 8mm or 5/16" if memory serves.

Go oem tank. My truck came with plastic, had garbage in it that put me in a couple bad situations. Granted after flushing it twice with water and rinsing with denatured alcohol it was fine but i had already bought a good used oem one from a mudder.

 

[oldschool4wheeling]

Pull it, clean it, new rubber hoses if any. I believe you got more trash than you can see.

If tank is bad refurbished it or get new steel tank.

NO POLY!

I chased crud/rust in my tank for months... Finally got new tank, sent carb to Jim C. and more fuel filters.

She runs like a champion now, no issues!!

 

[Northbound]

I've had Weber issues with trucks in warm weather and I could always cure it with an electric fuel pump and an adjustable regulator.
I use a regulator with a built in return mounted to the firewall as close to the carb as possible. this effectively shortens the feed line
to the carb. The pressure side runs from the pump to the adj. regulator. It splits internally with an output to the tank and one to the carb.
It virtually eliminates any possibility of cavitation or vapor lock in the system. I use a high flow pump like a walbro. If you ever go fuel injection
you'll already have the pump. Some regulators have a 1/8 npt port for a gauge so you can dial in the pressure. If not I would add an inline fitting to support a gauge.
Mr gasket makes a pretty inexpensive one that looks suspiciously like the doubly priced Holley

Mr. Gasket Fuel Pressure Regulators 2015

The Walbro style pumpe were used on many Ford trucks with dual tanks. There are a lot of brands and prices. I've run this cheaper brand on a truck for over 8 years then had an expensive replacement fail in two. Parts are hit and miss anymore so if just for testing pruposes I'll buy the cheaper. If it works then replace it when or if it fails

http://www.autozone.com/fuel-systems/fuel-pump/premium-fuel-fuel-pump/563488_478956_6210

I've had Weber issues with trucks in warm weather and I could always cure it with an electric fuel pump and an adjustable regulator.
I use a regulator with a built in return mounted to the firewall as close to the carb as possible. this effectively shortens the feed line
to the carb. The pressure side runs from the pump to the adj. regulator. It splits internally with an output to the tank and one to the carb.
It virtually eliminates any possibility of cavitation or vapor lock in the system. I use a high flow pump like a walbro. If you ever go fuel injection
you'll already have the pump. Some regulators have a 1/8 npt port for a gauge so you can dial in the pressure. If not I would add an inline fitting to support a gauge.
Mr gasket makes a pretty inexpensive one that looks suspiciously like the doubly priced Holley

Mr. Gasket Fuel Pressure Regulators 2015

The Walbro style pumpe were used on many Ford trucks with dual tanks. There are a lot of brands and prices. I've run this cheaper brand on a truck for over 8 years then had an expensive replacement fail in two. Parts are hit and miss anymore so if just for testing pruposes I'll buy the cheaper. If it works then replace it when or if it fails

http://www.autozone.com/fuel-systems/fuel-pump/premium-fuel-fuel-pump/563488_478956_6210

Thanks will give this a look because I was going to swap in a 6.0. I've got a 5.3 in the 40 and there's lots of benefits to that, but wanted to keep the 45 true, but only if it can be driven

 

[FJ40Jim]

Engine cutting off under braking can also be low fuel level in the bowl. The jets are on the back side of the bowl, so braking sloshes the fuel forward, uncovering the jets.

Fuel level could be low due to restricted supply, weak pump, dirty needle & seat, carb inlet screen...

 

[Nottajeep]

Looks like the source of my problem is the tank. Best just to replace instead of cleaning?

View attachment 20170303_191047.jpg

 

[Rock40]

If it's not leaking, have it cleaned. You can likely remove much of it yourself and I'd try soaking it in a bunch of Xylene or similar solvent first. You could also take it in and have it "boiled" out at a radiator repair place or similar. What'd I'd do would be dependent on how hardened the crap is on the bottom of the tank. Good luck, I think there's value to keeping that 45 tank.

 

[Pin_Head]

Radiator shops do fuel tanks as a side line. Last time I did one 12 years ago, it cost $60. Maybe it is $100 now. They boil them out, braze up any holes and seal them inside and out.

 

[Nottajeep]

Good idea! Will pursue this option first.

 

[sggoat]

Just recently had a similar issue. 40 would run fine up to 55, then start bucking and then die(like you just shut the ignition off). Very random. Fuel filter showed no trash to speak of--got what I thought was good fuel flow out of the pipe to the carb(I have a parallel electric fuel pp). Problem got worse--I decided to drain the fuel tank and look around inside. Pulled the flex line off the tank to drain into a clear jar(hoping to see trash) after waiting ~2 mins for the pencil-lead sized stream to fill the little quart jug, I figured there must be something in the line or tank restricting flow. Blew a little air back into the tank and heard a little pop, then a lot of gurgling--now I know something is in there. Now I get a full, large pencil-sized flow out of the pipe--time for a tank clean--
Found 4-5 small (what looked like) small pieces of a cardboard-like material in the tank---no clue where they came from)
Tank cleaned and flushed--no trouble since.

 

[oldschool4wheeling]

Radiator shops do fuel tanks as a side line. Last time I did one 12 years ago, it cost $60. Maybe it is $100 now. They boil them out, braze up any holes and seal them inside and out.

I wish I would have known about that when I changed out my tank on my 79. I would have liked to have kept the original, but wound up buying a steel aftermarket.

 

[Nottajeep]

I got the tank out now. Everything on the bottom is hard like PO lined the tank previously.

Thinking a new tank might be the best route.... Thoughts there?

Found a radiator shop to consult.

Gas Tank Clean and Repair and Recoated

 

[oldschool4wheeling]

Let radiator shop clean up original.

 

[Nottajeep]

I called the radiator shop.
$125 to clean and coat a normal tank with red kote.

If a liner is already in the tank, they need to cut the tank in half and scrape it out.
Price goes up at that point to an ambiguous amount.

New OEM tank come on down.

Anyone have a good line on the 8mm/5/16" hoses. Napa Auto, etc..?
I previously installed 3/8" hoses from Orielly's before and after the filter. Wonder if that size is acceptable to also run from tank to hard lines or do I need to redo those with the official 8mm?