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 Post subject: hard starting 907ie fuel pressure
PostPosted: Tue Mar 31, 2015 4:48 pm 
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Joined: Fri Jun 13, 2014 6:26 pm
Posts: 25
Location: UK Staffs Derbyshire border near Derby
model: 907 I.E.
year: 1992
Hi all I have been having lots of problems recomisioning my 907ie it had been dry stored for over 10 years until last year, I got it running last year after a good clean through and fresh fuel and it was spot on started first touch and ran well it was ok for a month or so. I then couldnt get it to start and found it had burst the in tank hoses, I replaced them but put the outside tank pipes back to front and primed the pump straight away I corrected the pipes and started the bike it took a lot of turning over to get going but went and ran well but only in my yard (not on the road). I had a few other jobs to sort on it so it wasnt started for a few weeks. Since then the bike has been getting harder and harder to start from cold, crancking for ages before fireing up, I bought a fuel pressure gauge and today hooked it up, I turn the key to prime and the gauge read a touch over 3bar about 44psi and held steady while the pump was priming, as soon as the pump stopped priming the pressure dropped to just over 1bar this drop in pressure only took a second or two, is this normal or is this where the problem lies, If so where should I be looking , the pump or the regulator? many thanks re Alistair


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 Post subject: Re: hard starting 907ie fuel pressure
PostPosted: Tue Mar 31, 2015 6:28 pm 
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paso grand pooh-bah
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Joined: Thu Nov 03, 2011 10:13 am
Posts: 761
Location: Scotland
model: 907 I.E.
year: 1994
it may well be normal, it will depend whether the pump has a non-return valve in the outlet. I don't think it does but I don't know for sure. Whether it does or not, the pump should start running immediately the engine turns on the starte,r so the pressure should be maintained while it is cranking and of course while the engine is running.

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1994 907ie
2017 Supersport 939
2015 Scrambler Classic
1982 Pantah 500SL (now sold)


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 Post subject: Re: hard starting 907ie fuel pressure
PostPosted: Tue Mar 31, 2015 6:34 pm 
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paso grand pooh-bah
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Joined: Thu Nov 03, 2011 10:13 am
Posts: 761
Location: Scotland
model: 907 I.E.
year: 1994
I just checked the manual the fuel pump indeed has a non-return valve. So either the valve isn't working or one of the injectors is dumping the fuel into the engine.

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1994 907ie
2017 Supersport 939
2015 Scrambler Classic
1982 Pantah 500SL (now sold)


Scotland


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 Post subject: Re: hard starting 907ie fuel pressure
PostPosted: Tue Mar 31, 2015 7:07 pm 
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Joined: Fri Jun 13, 2014 6:26 pm
Posts: 25
Location: UK Staffs Derbyshire border near Derby
model: 907 I.E.
year: 1992
Cheers for the reply what do you you think my best course of action should be to trace the problem I thought about blocking fuel line somehow before it reaches injectors to see if pressure is held by pump just a fast flick of the key to get near 3bar and see if it holds. What do you think. Thanks again for your help re Alistair


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 Post subject: Re: hard starting 907ie fuel pressure
PostPosted: Wed Apr 01, 2015 8:08 am 
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paso grand pooh-bah
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Joined: Sun Jul 18, 2004 12:00 am
Posts: 5426
Location: southern Germany
model: 750 Paso
year: 1987
do you have spark?


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 Post subject: Re: hard starting 907ie fuel pressure
PostPosted: Wed Apr 01, 2015 4:13 pm 
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Joined: Fri Jun 13, 2014 6:26 pm
Posts: 25
Location: UK Staffs Derbyshire border near Derby
model: 907 I.E.
year: 1992
Yes sparks seems ok I have hooked up a gauge just off the end of a pipe that exits the fuel tank delivery I flicked the key till the pump reached 3 bar then turnned off the pressure it held for hours. I then took the pipe off the exit side of the injector rail and hooked it up so the fuel bypassed the injectors but went straight to the regulator, I primed the system, once stopped priming the pressure held at just below 3bar at around 38 psi for 5 hours. So the loss in pressure appears to be somwhere at the injectors, It looks a pain to get them out but looks like thats my next port of call, I havent much experience with injector and I dont know If they can be repaired. Cheers for the advice all re Alistair :thumbup:


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 Post subject: Re: hard starting 907ie fuel pressure
PostPosted: Wed Apr 01, 2015 8:43 pm 
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Joined: Tue Jul 24, 2012 8:54 am
Posts: 283
Location: Cairns, Queensland, Australia
model: 907 I.E.
year: 1992
Hi Alistair.

The Injectors come out pretty easily, just look out for all the little small things that usually fall off when you least expect them too. They usually drop where you can't get to them too. The fuel rail has a couple of half shells for each injector with a circlip to hold it all on. The 2 bolts per injector, disconnect the electrical connector and that should be it. The Injectors should slide out after that. I had a set cleaned and tested about 3 years ago. They cleaned them all up with an ultrasonic cleaner, put a kit through them and then pattern tested the spray.

Cheers.

Nick.


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