Problems after 1989 3PG HEI upgrade, need help please!

[rxguy1976]

Our cart (1989 Marathon 3PG), was having issues with weak and intermittent spark. Kept quitting, and spark was very weak/erratic. Got the parts for the HEI upgrade, read all the pages on the sticky. (Thanks to everybody!) Completed the install. The cart started right up...took off like I was hoping it would......only thing is, it will not stay running for more than 100 feet or so.

It takes off with lots of power/acceleration, runs about 100 feet, and cuts out and then stops if you don't lift off the gas. When it starts to stall, if you lift off the gas, and then reapply throttle, it will takeoff again.

I checked the pulser, 147 ohms.

Help!!!!

Thanks

Parts used: BWD CBE4 ignition module, BWD E41 Coil. I used the existing wiring and harnesses as much as I could, did not do a total rewiring with new wires. Also installed a new plug.

Followed the schematic in the sticky.

[cart around]

Did you connect the fifth wire to ground?

Sometimes you have to switch the red and blue pulsar wires to see which way it runs better.

And finally, it sounds like you have more of a fuel problem than anything.

[rxguy1976]

Yes, I did have a 5th wire for the ground. It was grounded to the same spot as the original igniter, on the ground post for the voltage regulator.

I did end up switching the red and blue wires to get it to run as good as it does. Before switching them it would run (slowly) but backfire and miss.

I will start checking what I can on the fuel system.

Thanks for the quick reply.

[rxguy1976]

Checked the fuel system. Blew out all the lines, no junk in them. Took out/inspected the pickup hose in the tank, replaced both in line filters. The fuel pump diaphragms were good, all were intact.

Took the carb apart, jets/passages were clean, float was within specs, the inlet needle was good.


Cart starts, takes off great, starts to lose power. If you feather the throttle, it will pick back up and take off again. No miss, no backfire.



New coil tests out ok as far as I can tell. Less than 1 ohm between + and -.

Positive lead to center pole about 7400 ohms.

Tried to post video links, only a 5 day member....

Any ideas?

[cart around]

Interesting. I'm not sure where to go with it. If it's spark, I would suspect that the module is heating up. If that were the case, feathering the throttle wouldn't help.

If it's fuel, the last thing to suspect is the cross drilled bolt that holds the float bowl on. If the bottom of the bowl is crushed in any, that gets blocked, and restricts flow to the main jet. Feathering the throttle would give it time to recover. Other than that, I'm out of ideas.

[rxguy1976]

The bowl on the carb is not damaged.

I have the igniter mounted on a big piece of aluminum channel as a heat sink. Used the grease that came with it to make sure the heat is transfered correctly. When I can post pics I will.

Working on this thing is quite frustrating.

I have a short video of the fuel pump pumping, plug out with starter turning motor over....it looks like the output is decent. I can post it after 7 days... :)

I also have a short video of the cart running on jacks stands that shows what it does. Again...it'll be a couple days before I can post.. LOL

Thinking like you, that it might be fuel related, when it starts to slow down, I have tried using the choke to see if that might keep it going. That didn't work, all it did was load the engine with fuel, so that when it restarted it backfired.

From reading on the internet about ignition control modules there's a small chance that it might be the problem.

I'm going to try a different ignition module, the auto parts store said I can just swap it out. Give it a try tomorrow. Will definitely let you know. Not sure what else to try.

Fingers crossed. :)

Thanks cart around for your help and suggestions..

[cart around]

What happens after it falls flat, and you feather the throttle? Does it keep repeating?

[rxguy1976]

Yes it keeps repeating. Falls flat, lift, reapply throttle, takes off again. Sometimes it will run for good for 100-150 ft then fall flat. Other times it will still run, but not go as far before it goes flat.


Fuel pump output:

ht tps://www.youtube.com/watch?v=EifHe0r1m6A


Engine running with cart on jack stands:

ht tps://www.youtube.com/watch?v=-2K9uHo-yxE

I will post link to pic of igniter installation tomorrow.

Appreciate your help. Thanks

[cart around]

I watched on my phone. Fuel pressure looks weak to me. Maybe someone else can watch and give their opinion. Sounds great when running. I will have to pull my fuel line off tomorrow to get a comparison. It's been too long to go by memory.

[Dabble Inn]

Boy, that 4 second video was quick. Before I watched the second video I was going to say the fuel pump output looks ok........

But after seeing it run is does seem like it's starving, hmmmm?