engine stumbles going uphill at highway speed

[loborph]

My engine cuts in and out when going uphill at speed. I'm guessing its a fuel flow problem. The fuel pump is new and carb was rebuilt last summer.
Maybe its carb float? Any ideas, or where should I start? (problem is not readily reproducible)

[Stuka]

how steep of a hill?

You may need to adjust your float level. Or your fuel filter may be getting plugged.

[moloss]

I would appreciate any replys...... my fsj has a similar problem except It goes fine up hills but will die going down hill (steep off road stuff) even though it has back fired going down a steep street.......when it dies after a steep down hill it will only start if you pour gas (and alot at that) into the carb........It's a 82 cherokee laradeo WT with a custom gas tank........could it be the pickup in the tank? it has a holly carb, is it the carb? will one of the off road carbs fix this? any and all suggestions are greatly appreciated!!!!!!! .......when it dies going down a steep rocking down hill and you lose your power brakes and steering it gets real interesting fast........thanks Chris

[flyboy]

It's the carb. Holley's are not the best for offroad. The new truck avenger has had some pretty good reviews. A Q-jet works well. The Edelbrocks don't seem to do well even with the offroad needle and floats. What you have was set up to tow a 36' sailboat down the interstate.

Terry

[tgreese]

Believe it or not, the stock Motorcraft 2V is a pretty good off-road carb. When I replaced my stock 2100 Motorcraft on my '73 304 CJ-5 with a 400 CFM Holley, it developed certain attitudes where it would not run. The Holley even had the tricked-out package - side pivot float, float damping spring, vent whistle, float baffle... but it still s*****d compared to the stock Motorcraft.

The Motorcraft carbs can be tweaked up to give better performance than stock too. Jets are available, and the power valve is the same as on Holleys*. AFAIK, three venturi sizes were available, 1.08" (450CFM) , 1.14" (520CFM) and 1.21" (575CFM). The venturi size is cast into the size of the bowl, 108, 114 or 121 repectively, in leetle letters that you may not be able to see till the carb is out of the car. (These CFM numbers may not be accurate).

If you buy a 2XXX series carb, be sure to get one with the float damping spring that came stock on Jeeps - it's a little coil spring that wraps around the float pivot shaft. Jeep came out with a tech bulletin advising to install this spring in '72 or '73, and AFAIK all Jeep Motorcraft carbs after that had a damping spring.

This only applies to the 2V Motorcraft - apparently the 4V Motorcraft (4350?) has other serious problems.

hth :cool: Tim

* somebody know of a source for aftermarket 2-stage power valves?

[tgreese]

BTW moloss, I believe the worst problem that the Holleys have off-road comes from the center pivot float - you may have one. The center pivot is known for working well in track conditions (ie lateral Gs) but not up or down hills. You can tell if your carb has a center pivot float by taking off the air cleaner and looking at the carb. The float bowl is a metal box that screws to the front side of the carb. It has a slotted screw-cap about 1/2" in diameter on the top, underneath which is the float needle. With a center pivot float, this screw is on the left-to-right center line of the carb. Side pivot floats have a needle offset to the left (passenger) side of the bowl IIRC.

hth :cool: Tim

[ July 27, 2003, 11:24 PM: Message edited by: tgreese ]

[dustinwagoner]

I had the same problem with an 84 wag 360. I replaced the float and haven't had a problem yet.

[moloss]

you guys are awesome..........later this week when I have time I'll get out there and see what I can figure out........thanks so much......Chris

[will e]

Originally posted by tgreese:

The Motorcraft carbs can be tweaked up to give better performance than stock too. Jets are available, and the power valve is the same as on Holleys*. AFAIK, three venturi sizes were available, 1.08" (450CFM) , 1.14" (520CFM) and 1.21" (575CFM). The venturi size is cast into the size of the bowl, 108, 114 or 121 repectively, in leetle letters that you may not be able to see till the carb is out of the car. (These CFM numbers may not be accurate).

If you buy a 2XXX series carb, be sure to get one with the float damping spring that came stock on Jeeps - it's a little coil spring that wraps around the float pivot shaft. Jeep came out with a tech bulletin advising to install this spring in '72 or '73, and AFAIK all Jeep Motorcraft carbs after that had a damping spring.
When I took my rebuilt by holley 2150 apart it did not have the damping spring. I will check the rebuild kit to see if it came with one. Any tips on how it is installed on the pivot shaft? I can 'read' an exploded diagram but the one with the rebuild kit is not too clear.

one other note on 2V and 4V carbs. They are rated differently so you cannot directly compare CFM's between the two. I can provide more details if you wish (I will have to look them up).

I am pretty happy with my 2150 except that Holley rebuilt it with out the sping or the screen that sits under the seat for the needle. A small piece of gasket caused me a lot of trouble.