Fuel pump question

On or around Mon, 19 May 2008 04:46:31 GMT, jg enlightened us thusly:

sometimes it'll go slow, so that it'll only idle and not run above idle, I had one do that. Mostly, though, I think they just stop supplying enough-or-any fuel and the engine stops. Of course, there are other reasons for non-supply of fuel so try checking the pump by arranging an independent

Note though that if the pump runs it's not necessarily delivering (enough) fuel.

I found with one of mine (an 87) that occasionally it was necessary to put a 12v feed to the fuel pump fuse, that would normally kick the pump into action. The relays can get a bit sticky with age and a proper 12v feed for a couple of seconds will normally get 'em going. Must be a reasonably common bodge because an AA man did it straight away when I couldn't get it going (it was raining, I was dressed smartly and I couldn't be arsed ferreting about)..

Thanks for comments. I ask because I know they have a finite life and this one must be somewhere near the end - I think it's "only" on the second one in 400,000km. The car was running badly mainly due to a slipping alt belt. When that slipped it seemed like a fuel problem and it still misfires a little with A/C + lights on and very occasionally cuts out for a few seconds (even with no elec. load always at the same place... no, it's not the pub).

Sounds like a loose connection.

I had a loose connection on a '83 RRC at the coil which generated similar symptoms. That was a carb fed V8 mind. I don't know whats on the '87 variety but if it had a coil then check the leads / connections are tight and clean.

Often such faults are the aftermath of dealers jet washing engine bays.

Lee D

Possible, but I do look out for those. It's just that I know the fuel pump's time must be near and wondered if the "happenings" (which are not in themselves too concerning) could be symptoms.

And with a RR of this vintage one of the possible causes is loose/dirty connections to the over-run relay mounted somewhere near the LH front suspension turret. Those cases that I have seen have caused a fully on/off situation but I can imagine an intermittant result too.

This relay is controlled by a vacuum switch at the rear of the RH rocker cover. I've had problems with that as well.

Don't overlook the fuel pressure regulator, either, but I don't think that the symptoms as I understand them point to that.

Have to look up what over run relay does. That's the car's RH or yours from the front?

"jg" wrote............

Car's left, nearside, kerbside, passenger side or on your left if you're sat in the driver's seat. :-)

Martin

The relay is energised in normal running. If a wire drops off, for example, the fuel is cut off. Function is to cut off the fuel on the over-run (high vacuum) controlled by the afore-mentioned switch.

RH/LH are conventionally from the driver's seat looking forward.

I found it using the manual, guess it depends on RH/LH drive - it's RH. Haven't had a look yet - quite confident it won't happen until go "there". Sounds like I'm making it up, but it's a RH long bend take pretty slow then up a moderate long ramp onto the freeway. Fine round the bend, fine up the ramp under mod acceleration then as it levels off and you start to ease up... silence. Then away we go again. Gearbox is so smooth I often have trouble guessing what gear it's in or whether the torque converter has locked - a mechanical action I believe. There are steeper hills, faster speeds, similar bends etc, but nah, only here only sometimes.