Here's the story. Son bought the bike 150 miles from home in another state. went to get it ran fine for longish test ride. he forked over cash and set out for home. Bike was flawless for about 60 or more miles. smooth and fast. then it sputtered and died. resorted a few time for a few miles. then had a friend come get hime with a truck.
He got it home managed to starts it once or twice and even get it around the block. well several brittle and broken hoses. we assumed that one of those broke and is the reason for poor runnings. Well he has to wait a few weeks to register bike (ran out of money). so he pulled and cleaned carbs pulled and cleaned tank.
fixed fuel pump fuse so now the bike wont start. if he pours a teaspoon of gas in each carb it will fire occasionally. battery dead took it out to charge. battery back still no start. High side of coil getting voltage. Fuel pump clicks and fuel in carbs now. but still no start!!

Several posts here about jumping the battery and trying to start with running voltage from car or jump box and taking 5 minutes or more of constant cranking to get bike to fire? Is the ICM resetting? are various components out of sync? Why the excessive start attempts seem to be a common answer?

I am an old car guy, got out when computers came in( actually stayed in but specialized in older stuff). II'm in Florida he's in Tennesse I've SKYPED a few times so i can see and hear. It just seems like its not firing. the occasional back fire from the pipes being loaded with vapor is about it.

I'm very puzzled as the bike ran so well for almost 90 miles between his trip home and the test ride?

Any ideas? Any one near Knoxville that could take a look see?
i'm convinced its something stupid or small I just can't figure out

 

Is the petcock open? Sounds almost like the tank got low enough and he didn't switch to reserve.

 

petcock was on reserve when running. That developed a small leak which we fixed. as we did the fuel lines. I'm sure fuel is flowing because the bowls are full now.

 

Does the f4 have a reserve? As far as I know my '99 has a fuel light and the petcock is just on/off. I believe it has 2 off positions and one on.

How many miles are on the bike? He may want to check at least the compression and perhaps the valves, particularly if the bike is higher mileage.

Could this be a sporadic fuel pump? If it ran well briefly when he poured fuel in the carbs this would be my suspicion. Maybe a blown fuel pump fuse is a hint?

Has he checked that he's getting spark? On a bike of that age and unknown history I would replace spark plugs just to be sure.

Could it be a bad coil or coils? Maybe someone local can loan him a set as they're not cheap to buy.

What is the resting voltage of the battery? Has he had the battery to an auto parts store to be tested? A weak battery can manifest in a number of strange ways. My bike doesn't idle well when the battery is low I think because the f4 doesn't charge at idle. I'd also check that it's charging at higher rpms--perhaps 60 miles was the distance it took to run down or least weaken the battery.

Are the jets stock or reasonable for the pipe?

How does the airbox look? Don't forget the foam filters in their own compartments--mine were disintegrated by the time I noticed they were there. I'd also go over the plumbing around the airbox as worn hoses could maybe be a cause.

Assuming reasonable jetting and a not clogged airbox this sounds like a sporadically failing component that is impeding spark or fuel supply.

-morgan