quad lta750 wont start

[Bigrustysr]

my quad 750 wont start pops and bangs and backfire but wont start using starter -but one pull with pull start fires right up but wont take gas until it warms up a while then runs fine (70mph):banghead

[Masteryota]

Assuming this is carburated, I would start with the choke and go from there.

[x-bird]

if it has a compression release mech for the pull start then it almost sounds like an exhaust valve issue.

[Bigrustysr]

its fuel injected doesnt have compression release -with 10:1 compression its takes all my strenth to pull start (I'm 75 yrs old- pull starting not a good option LOL)

[Masteryota]

Ahh, fuel injection, my specialty. I know those big quads are liquid cooled, and this symptom sounds like a coolant temp sensor has shorted. The ecm will richen the fuel mix on cold starts, and if the sensor is reading that the engine is warm, then it will run crappy cold, and then once the engine warms, it runs like it should. Without knowing the particulars, anything more would be a guess.

BTW, very nice machine, always wondered what power steering on a quad would be like.

[Bigrustysr]

thanks masteryota-can i unplug coolant sensor to test?-my next thinking was maybe crankshaft position sensor by the way it pops and backfires like a timing problem- hard to get to ckp sensor tho -any thougts will be appreciated

[Masteryota]

You can unplug it to see if the condition changes, but will likely run like it does now. If you have an ohm meter, you can test the resistance cold and then hot and compare it to the factory spec, if the resistance is the same hot and cold, then it most likely shorted internally.

As for the crank sensor, I would think you would have more issues than cold start problems, and would hesitate almost all the time, or bog or ping on acceleration.

I haven't been able to find any specs online, may need to call a dealer and see if they can tell you the spec range on the coolant temp sensor.

[Bigrustysr]

power steering great in deep mud and sand but at high speeds its a little touchee- lite hand needed

[Bigrustysr]

toke it to local dealer a while back (2 times) worked ok for a day- then right back to the same Service manager is a Jerk -he says I dont ride it enough i ride it everyday checking fences -wont take it back there-will look for another shop I guess

[Masteryota]

Originally Posted by Bigrustysr

toke it to local dealer a while back (2 times) worked ok for a day- then right back to the same Service manager is a Jerk -he says I dont ride it enough i ride it everyday checking fences -wont take it back there-will look for another shop I guess

Unfortunately, thats the word everywhere, unless you are buying accessories or tires, they pretty much shun you and make you feel stupid.

I had problems with my local suzuki dealer, oil leaking from brand new bike, I knew where it was coming from, but still under warranty. They looked at the bike 3 times and claimed no leak found, I pulled it down to the source of the leak, photographed it, ordered the part through their parts dept, and called suzuki corporate before I took it back. Then, and only then, did they fix the problem, and then showed me the door and pretty much said don't come back.

[Bigrustysr]

I have service manual i got off line (cant remember where)if u want a copy i could email to u if u want. it has all spec's