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[Richy2spanners]

Hi Guys, I'm scratching my head again and would appreciate a point in the right direction please. I was riding home Last night. All ok and plenty of fuel. When she starts spluttering and misfiring. It felt like the power completely dies and suddenly roars into life. A lot of backfiring, a lot of backfiring! I just pointed it home and tried to hang on. I was on the dual carriageway so tried to keep it going. But it got weaker and weaker until it died. Recovery man suggested spark plug. I had one at home and changed it. Bike turns over but does not fire. Any suggestions please?

[Tim NZ]

Fuel pump? Not exactly the most reliable component on the bike...


Check the main 20a fuse; apply a wriggle test.


Check the fuel pump relay...

[Gwilly]

Take issue there Tim, never heard of a pump failure on these, and at £417 plus vat there would be an outcry if it happened regularly..

Nearly always fuse carriers, relay wiring connectors and bad earth frame to battery..

Waggle is good.... Isn't there some kind of fault diagnostic light arrangement on EFI's..

Worth a check in case it throws up a component fault...

[scotty]

Had this a couple of times , batt connections on efi bikes are crap very brittle brass on my c5 only thing holding earth connection together was rubber boot giving intermittent failure other time it was a dud cell in battery on iron barell with boyer ign and we know how boyers go if they dont get full voltage. I discarded the efi terminals and soldered on a pair of heavy duty ring ones also taped up the batt leads to stop them flapping around.

[Rattlebattle]

+1 what Gwilly said. Almost certainly a poor connection somewhere. In my case, showing similar symptoms, it was the tps connector. This had loosened and became looser to the point that the engine popped and banged an awful lot and eventually wouldn't start at all as the engine choked up. It could also be a loose or broken battery terminal connection. I doubt it's the fuel pump, a Keihin item, but it could be bunged up (technical expression) if the filter is clogged, but my money is on a connector or wiring break. The OP might try reading the stored fault codes. It might give a clue.

[papasmurf]

On the subject of fuel pumps, even if it does fail I seem to remember a thread on the forum a few months ago about repairing the pump for £60.

[nigelphoto]

Fuel pump relay failed 10 miles after I collected my B5 brand new from the Dealer - cost (under warranty) I was told is less than £10. It might have helped if the Dealer had pdi's the bike but, as he explained to me, 'it was raining yesterday, so we couldn't test it'!! Also, Richy even if the battery pd tests at 12.2 v the pump will struggle to pressurise the injector. It must be >13v or you will get pharting and backfiring and eventually Death by Fuel Starvation.

[Beezabryan]

A 12v battery in good condition & fully charged stands at 12.6v.
>13 I assume is a typo ?

[Dennis C]

As Bryan says a 12v nominal battery will hold 2.1v per cell = 12.6v.if the battery connectors are bad, would the starter motor work?.

[papasmurf]

A lot of motorcycles with EFI and electronic ignition will struggle to start with a battery less than 13 volts.
It is not just a problem with Enfields.