Braking causing engine to die

The little plastic connector at the brake booster, that goes to the vacuum line, is a one way connector. It is probably defective. They are pretty cheap to replace. That ought to fix you up.

Spdloader

That could be it. There are no power brakes when it dies while moving and applying the brakes. If the valve was working, there should be at least some power brakes for awhile as I understand it. When the rains stop, here in the west, I'll check it out. Thanks,

It'll definitely do it. I used to keep 'em on hand in the shop. It's such an interesting combination of symptoms, it really points to that little connector. They cost, or used to, around 5 bucks.

Spdloader

I finally got over there to check this out. It wasn't the check valve.

I even clamped the vacuum hose off to the booster and still had the problem.

I did find out more though.

If you are not moving and put the brake on, no problem. If you back up a little and put the brake on, no problem. But if you pull ahead a few feet and put the brake on, it dies.

You don't have to be going fast at all, for it to die, when this happens.

I've looked for loose wires and also dropped the float level a bit, just in case. Any more ideas? Thanks,

Torque converter locking up? does it jump any when it does it, or just die out?

Sorry it didn't help ya Bob. I'm out of ideas, the post about torque converter is the next route I'd pursue. Good luck.

Spdloader

It has a manual transmission. Just dies, no jump or anything. I only have to move it a few feet in forward and put the brake on and it just dies.

OK, Thanks for trying anyway. :O)

hmmmm, What year is the truck? Carbureted or Injected?

It's a Holly, two barrel carb. 1981 f250 ford 4x4, manual trans. All the emission stuff has been disconnected and plugged.

I turned the float screw down a half turn below normal, just in case.

If it was the carb, I would think it would still die with backing, as the gas would still slash forward, after hitting the back?

It's possible there is a broken wire somewhere and the momentum from forward braking is breaking the circuit. I'd check all the wires I could with an ohm meter while wiggling them. If there is a break, it'll show up.

Tony

On Sat, 21 Feb 2004 22:11:38 +0000, Anthony rearranged some electrons to form:

Does it do it if you are coasting in neutral, or coasting with the clutch disengaged?

got me stumped, on an older vehicle like that, there is so little that could be causing it. Strange!

what about the ignition on the old beast, anything electronic on them in that era that could act up?

what about braking while in gear, does it quit then? Does it start running again when you let off the brake?

How about hooking up a timing light to it, take the light in the cab, brake while in gear and see if the timing light stops flashing when you brake. If it stopped flashing it would be ignition related, if not, then fuel?

If I am getting too far out in left field, let me know.

l8r, Jeff

Yes, I'm sure it's possible there is a bad wire somewhere, but so far, I haven't located any. The interesting thing is, it takes so little forward momentum to cause it to happen. I can just move it a few feet in forward to cause the problem to happen.

This is something I still have to check. I can't remember if I checked it this way or not. :O) So far, I know it does it with my foot on the clutch petal, disengaged.

I also want to check it by using the emergency brake to stop it instead of the foot brake Thanks,

Hey Jeff, You're not getting to far out for me. :O) When it dies, it dies, there is no coming back. Letting off the brake doesn't help, it's already too late. This might indicate, more of an electrical problem, but it always starts right back up. The timing light sounds like a good idea.

I'll have to check the braking in gear. I can't remember if I tried that yet.

Another thing I'll try is pull the choke on just a bit and see if it'll keep running. Although, I can't imagine what in a holly two barrel carb would cause this.

Ok, all you guys have given me some more ideas to try. I'll try them all and some more and get back to you. It may be a few days. Thanks,

my 2 cents worth:

sounds like ignition, something loose or shorting on primary or secondary of coil? Getting pinched to ground or breaking open when you stop.

or vacum - when you stop while moving forward the engine is rocking and sucking air somewhere?

can you duplicate this by maybe rocking the vehicle while it is idling? Or maybe jack it up with a floor jack to try to twist or move whatever the heck is wrong?

Ok, I had just a little time today to look at the truck again. I tried it with the manual choke out about a half inch. It tried to die, but didn't. So, I'm going to get a carb rebuild kit and go through the Holley two barrel to see what I can find.