748 Wont start

[rgramjet]

I sold my 748 on Monday but now Im having a problem.

Guy came out to look at it.  Started it up and let it run for a little while.  All of a sudden it sounded like one cylinder went, then the other.  It turns over fine but will not catch now.

Anyway, the guy still wanted it, took it home, changed the plugs and its still not starting.  He also said the plugs look fine.  Any ideas?

Thanks in advance!!!

[johnster]

Did you try putting gas in it?   

I kid, I kid....

Seriously though, I wonder if there might be a gas "starvation" issue....maybe a clogged fuel supply line, or an injector problem?? 

If it ran fine for a little while then died, it tells you that the enigine runs OK, but it got deprived of something (maybe gas) after a little while....

-I would check that first, and if you can verify that the injectors ARE getting gas, and the plugs are getting electricity, Then I would maybe suspect a faulty ECU....

Good luck, and keep us posted!!!

[uclabiker06]

Can't believe the guy still took the bike unless he was a mechanic or something.

[rebelpacket]

How old are the belts on it? 
What do the spark plugs look like?  Check for spark first, then go from there. 

[rgramjet]

Can't believe the guy still took the bike unless he was a mechanic or something.

Yeah, same here!!  I strongly urged him to leave it overnight so I could change what I thought were the plugs and get it running properly.  Hard on prevailed!  lol

Update: Just got off the phone with the mechanic he has looking at it.  Said upon first glance, he thinks its the coils which run $170 each for the parts.  Also said he isnt hearing the fuel pump priming when the key is turned to the on position.  He said he checked all the fuses and they look good.  Too much coincidence to have coils and fuel pump go bad?

[rgramjet]

Another update,  buyer said this will all be no problem as long as i pay for the parts.  I told him Id rather give him his $$ back and Ill do the repair myself in light of the fact that I came down $500 off my asking price. Of course, while I held his deposit check, I got 2 more calls from people wanting to look at the bike. 

Take off Coils and fuel pumps are a dime a dozen on ebay.

[rgramjet]

Update:

Buyer has bike with mechanic, says the fuel pump doesnt prime when the key is in.  He put new relays in and got it to start.  He test rode it for 1 mile then it shut down and wouldnt restart.

Alex at Ram Cycles, says he might have a set of 916 coils that I can try.  Doesnt answer the fuel pump issue though.

Buyer wants $$ back so thats what Ill have to do.

[Slide Panda]

Do you think you've got a short some place?  Does the pump still prime now?  Or is the relay shot again?

[rgramjet]

I have no idea.  Thats probably a good guess now that I think about how it puttered out.  Wish I had it here so I could troubleshoot a bit....

[Slide Panda]

Once you get it back, the 1st thing I'd be checking is to see if that pump primes w=once you have the key on and the kill switch to run (and bike in N)

You should hear a short buzzzz from the tank area (seat off might help you hear).  If there's no noise then that relay to the pump might have kicked off again.  Luckly relays are cheap... swap in a new one - but expect that one to crap out.  If it does then you've got some other issue. 

Now I'm getting to guessing, since electrics aren't my strong suit - but if the relay blows again I'd be getting to wonder if my voltage regulator isn't at fault... but I'm just theorizing.

You should check for spark since that's easy - but I seriously doubt it's your coils.  I bet the problem is further up the stream

[rgramjet]

Im picking it up tomorrow and should have a little time to throw at it......I heard Colemans Bike a palooza is tomorrow, Yuu going?

[Scottish]

Any news on this? I ask because I'm having a similar problem with my fuel pump.

[rgramjet]

1st mechanic found loose negative battery terminal.  Its still at Ram and I should know something on Monday.  Its my understanding that relays dont like loose neg battery terminals.....hopefully thats it.

[Ducatista]

1st mechanic found loose negative battery terminal.  Its still at Ram and I should know something on Monday.  Its my understanding that relays dont like loose neg battery terminals.....hopefully thats it.

Relays in general don't like being flipped in rapid succession.  I had a brake connector that was arcing against my frame and it kept on blowing the main relay. 

[clubhousemotorsports]

In 10+ years wrenching on Ducatis I have never seen a bad coil on a fuel injected Ducati.
fuel injector relays ? yes. I believe that the ecu relay sits beside the fuel injection relay and they are the same part, you can swap them and see if the pump cycles.
 make sure that there are  no shorts in the system. My 851 once had a wire that had chafed at the fuel pump to fuel tank connector. it would blow fuses.
Also look for a wire connector that has become dislodged from its housing at the tank to harness connector.
good luck.