70's chrysl. fires but, doesn't run

My moter will fire with ether, but won't stay running...<br />I think I set the timing correctly...<br />The key is alright in the flywheel...<br />How do I test the fuel pump?<br />Also, it backfires out the exhaust.<br />It;s an 85hp<br />Thanks, all Bo

Re: 70's chrysl. fires but, doesn't run

First off, never use starting fluid on a two-stroke. It is like running a 4-stroke without oil---bad news. Use "Sea Foam Deep-Creep" in the spray can for decarbing the engine. But also, it doubles as a great two-cycle starting fluid. I keep a can onboard just in case. But you're on the right track with the fuel pump.<br /><br />The problem is carb or fuel delivery.<br />My first attack to this problem on that motor would be to disconnect the fuel line at the carb, put the line in a jar ,and hit the starter. If it pulses fuel, it's ok. I highly suspect you'll need to order a new fuel pump kit. The diaphram fails about every other year under normal conditions. This is because of the enhanced ,no-lead formulations of modern fuels.<br />The alcohol eats the rubber.<br />If it did pulse fuel, the problem is a clogged pick up tube, or other orafice in the carb.<br />Finaly, check compression. The reason being that the fuel pump operates on the motor's compression...No, or low compression=motionless diaphram=no fuel delivery.

Re: 70's chrysl. fires but, doesn't run

The fuel pump is painfully easy to rebuild on these motors- The kits are available from Napa and usually are ~10 bucks -- Would start there- Did the motor sit with old gas for a while? If so you will need to clean / possibly rebuild the carbs- Do not spray carb cleaner in there- just drop the bowls and then clean everything- These motors have to have 50:1 oil ratio and when you spray starting fluid or carb cleaner and crank motor you are taking away lubrication-

Re: 70's chrysl. fires but, doesn't run

Thanks GuYs...<br />I'll start here and go... Bo

Re: 70's chrysl. fires but, doesn't run

I had the same problem with my 85hp. Backfiring is more than likely timing. Find TDC for all three cylinders and mark them on the flywheel then put a timing light on it and make sure your firing order is right.

Re: 70's chrysl. fires but, doesn't run

If you disconnected the plug wires make sure you hooked them up right. If you reversed a set of plug wires this will also cause a back fire.