Low Revs Issue after Fuel Pump Replaced

[RandyMam]

Hi All,

 

After sitting for 1 year I went to start my R1100s BCR and found the fuel pump was seized.

 

I have now replaced the seized fuel pump using a kit from Euro MotoElectrics, but I cannot get the bike to start/run at low/min throttle. I did find that the right side cable was not properly seated into the throttle body (thanks to previous forum post) and fixed that. It seems to run smoothly above 2500rpm but below that runs rough and will not idle below about 1300rpm (I adjusted the cable at the twist grip to acheive this). Under normal riding (1st gear only so far) it has low power and knocks (pre-ignition) at low revs. I am about to drain and use fresh fuel as this does sound like an issue with too low octane. Any ideas appreciated...Many TIA

[dirtrider]

Hi All,

 

After sitting for 1 year I went to start my R1100s BCR and found the fuel pump was seized.

 

I have now replaced the seized fuel pump using a kit from Euro MotoElectrics, but I cannot get the bike to start/run at low/min throttle. I did find that the right side cable was not properly seated into the throttle body (thanks to previous forum post) and fixed that. It seems to run smoothly above 2500rpm but below that runs rough and will not idle below about 1300rpm (I adjusted the cable at the twist grip to acheive this). Under normal riding (1st gear only so far) it has low power and knocks (pre-ignition) at low revs. I am about to drain and use fresh fuel as this does sound like an issue with too low octane. Any ideas appreciated...Many TIA

 

Morning RandyMam

 

I doubt that you are seeing (pre-ignition) if your problem is just in first gear at low revvs as pre-ignition means it is firing before the spark occurs. Your knock sounds more like it is not firing correctly after spark occurs (spark knock or combustion knock). Usually from lean operation or very low octane fuel.

 

If your fuel pump was seized up from sitting then your fuel injectors are probably also effected from the same bad fuel.

 

You can T-R-Y a heavy dose of Techron with a tank of new fuel but if it is the injectors being effected by the stale fuel then I have my doubts that anything short of removing injectors & sending them out for a cleaning & flow test will help.

 

Or you could still be fighting low fuel pressure or low fuel flow due to an in-tank high pressure hose leak.

 

You might run a fuel return flow test just to verify that you have enough fuel flow at enough pressure. (it does run at higher RPMs so this is probably not the problem but should be eliminated from the list)

 

You didn't provide enough information to be precise on the cause of your problems but fuel injectors with a vary poor spray pattern would probably be where I started looking.

 

 

[RandyMam]

Thanks DirtRider.

 

 

The original fuel that was associated with the seized pump was never passed through the fuel system. The residual fuel in the system most likely has "varnished" the injectors.

 

I topped up with 10L of fresh 98 octane fuel and went for a short ride including short bursts at WOT in 1st, 2nd and 3rd gears. On my return I found that the lower revs have smoothed out a little allowing 1200rpm idle.

 

I work away from home during the week, so when I get back home on the weekend I'll try a dose of injector cleaner.

 

Cheers

[Lowndes]

RandyMam,

 

If the Techron that Dirtrider suggested doesn't resolve the injector problem for you, you might consider Injector Rehab in NJ.

Injector-Rehab can clean and flow test your injectors with print-out report. Watch the short vids on their site.

 

Or, you could replace your OEM EV2 injectors with EV14 (R1200GS) injectors with a complete kit from them: EV14 Injector Replacement Kit.

 

I did this on my '99 R1100S last fall and then again on my '99 R1100RT this spring. This is a very simple "plug and play" swap, didn't even need to remove the tupperware on the S, just the elec connector, fuel connector, and the two Fillister head screws holding the small injector bracket. EZPZ, 20 min job. Excellent results, runs much better.

 

Keith Gibbons is the owner and has posted on several BMW forums.

 

[RandyMam]

Well thanks for the suggestions and help. Today I perservered with the injector cleaner, 375ml in 10 litres of 98 octane fuel and approx 80km ride at 4-5000rpm seemed more like single cylinder operation at times. This did not really help so decided to check injector spray patterns. Engine started with power unplugged from right injector and there was little difference in idle. I pulled injector and put the power plug on - no spray when I pressed the starter. Checked the power plug and found one of the female terminals had retracted up inside the plug shell and was barely making connection. Corrected this and tried the starter button again to see a nice spray. Reassembled and all good now clean idle and !! Thanks also to this youtube vid...