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I have a kawi FD791D fuel injected v twin on a scag mower. It was working fine one day and the next nothing. It pops out the intake and backfires out the exhaust while cranking but never starts up, sounds like it wants to. Checked fuel pressure from the fuel pump by plugging the line with my finger, and it seemed to be making decent pressure, replaced the fuel filter, checked spark has spark on both cyls, compression is good. What commonly goes wrong on these things? Any ideas. This thing has all sorts of sensors and crap on it what ones should i check, crank sensors, fuel pressure sensors? Not too sure on these fuel injected engines?

Start with the basics.
Slip off the rock covers and verify the approximate valve timing by rotating the engine by hand with a stick down the plug hole.
Check the valve lash if it is excessive on one valve chances are you have bent a pushrod.
Kawka use very thin pushrods which are the fail safe device on their engine and they bend to avoid doing major damage to the engine.

Next check you have spark at both plugs.

Then check the ignition timing by spraying some starting fluid down the air filter hole.

if the engine does not fire then check the flywheel key is not sheared.

After that you are looking at the electronic control system which AFAIK is not checkable without the Kwaka tools so you are down to replacing each and every sensor one at a time till the faulty one is found and you have a shed full of perfectly good used sensors.

The best way to avoid throwing parts at it and get to the bottom of the problem, is to get the shop service manual and go through the troubleshooting check list and do all the test in order to get to the problem.

this is one of those times that you could chase your tail and waste time and money getting to the bottom of the problem.

ILENGINE said:

The best way to avoid throwing parts at it and get to the bottom of the problem, is to get the shop service manual and go through the troubleshooting check list and do all the test in order to get to the problem.

this is one of those times that you could chase your tail and waste time and money getting to the bottom of the problem.

Click to expand...

right

As posted you need to start with the basics and a plan. This manual should help you with both.

http://www.mymowerparts.com/pdf/Kaw...FD791D-DFI-KAWASAKI-SERVICE-REPAIR-MANUAL.pdf