250 running on 3

[daves69]

I rebuilt this 250 about ten years ago. Got it running but didn't put it on the road. Now here I am, changed the fuel pump and got it running. It only runs on the every second cylinder though. It gets fuel but no spark in 2, 4 & 6. Anyone out there had this before?

[69GMCLonghorn]

This is a special design specific to only that engine that helps with fuel economy. Just drive it on 3 cylinders and laugh like a little girl as you pass the other guys at the gas stations...

Ok, seriously: Start narrowing down the problem by starting at the dist. cap. Check the leads inside and make sure they're clean, not corroded, broken, etc. Check for spark where the plug wire meets the cap by pulling the wire loose and holding it about a 1/4" from the lead on the cap. See if the spark jumps. If it does, then move to the spark plug and do the same thing. Hold the wire about 1/4" from the plug lead and see if the spark jumps. If there's spark there, then shut the engine off and pull the plug. With the plug wire attached to it, have someone bump the engine over while holding the plug close to the block. See if the spark jumps. Someplace in this process, you're NOT going to have spark and that is going to tell you where the problem is. If you have SOME spark, it has to be either the cap, plug wire(s), or plug(s). These are simple systems.

Good luck and keep us posted on the outcome.

[daves69]

Thanks. I'll look a little closer at things. When I rebuilt it I replaced everything. I'm about to order an HEI set up so that will likely solve the problem anyway.

[vectorit]

I'm no expert on inline sixes, but the fact that you have no fire in all your even numbered cylinders sounds like something is not put together right.

What are you using for ignition? just original style points and coil? or are you using something other than OEM type stuff?

[daves69]

I was wondering the same myself. It's all stock. I had the head redone by a guy in town who knows 250's. Then I changed out the rings and bearings. I put a stock cam in it. The rebuild parts were after market stuff. I was 16 at the time of the rebuild but wasn't a complete stranger to rebuilds.

[big blue 72]

sounds like one o 'em high fallootin Caddylac cars that runs on just one bank.
Prolly gets ya up to 'bout 22 miles a gallon

[smallblock kid]

i had something similart to this but i dought it could be this
when i found out it was firing on only 2 cylinders i loosen up my rockers a little bit and and went to firing whoever tighten them down tightend way to far

[daves69]

I was wondering about that. I'll be at the shop in week to get back at it. If I can't find the problem with the distributor etc I'll take the valve cover off and take a look. Thanks. Thanks for all the feedback guys.