Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing '93 Plus 8 Fuel Pump Problems

I am working on my Father In Law's '93 Plus 8 back on the road. It has been laid up for about 2 years and has a fuel pump issue. The pump does not kick on when the key is turned, and thus the car does not start. I was able to get the car started by jumping the fuel pump directly to the battery which pressured fuel in the system. I took off the jumpers and the car started right up and sounded great and it ran for about 5-10 seconds until the pressurized fuel was burned up. Since it starts the only issue is getting that fuel pump running. I'm ready to get this beauty back on the road.

We checked the fuses (including the inline one next to fuel pump, the two behind the glove box, and other fuses in the main fuse bus), we tested the inertia/crash switch (removed and tested with ohm meter) and we replaced the 2 Bosch fuel pump and ECU relays behind the glove box with Bosch AFU2913L/986AH0602 relays (originally Bosch 0332014112) and still no go.

Does anyone have any thoughts on other things to check or possible loose connections somewhere? I've read the inerita switch wiring can sometimes go bad. Anyone have experience with that and how did they diagnose and resolve?

Is it a bad idea to disconnect the fuel pump wires and put in a temporary circuit with an inline fuse from the battery to the fuel pump with a on/off switch to run the car for 5 minutes because I'm itching to take it for a quick spin?

Scott, sorry I have little knowledge of your fueling system however as you deduced there is a safety system though perhaps not inertia, more along the lines that if the ECU does not detect an engine turning over/running signal then the fuel pump is denied an electrical supply. I think to detect engine turning over the system requires to detect air flow. if you have the flapper type air measurement system I think there is a switch activated within the flapper mechanism, which seems unlikely to be the issue, but it will no doubt have wiring and connectors between it and it`s input to the ECU and dependent on that input, an output from the ECU to a relay to then bring on the pump...

I suspect that whatever system you have you will find a brake-down of it`s operation at GoMoG.com, as the webmaster there has researched all sorts of EFI possibilities for Morgans.

Good luck.

I had the same issue on my TVR V8S and did all of the things that you have done. In the end I traced the wiring from the pump and found that someone had fitted an immobiliser rocker switch in the circuit, in my case in the boot, that I must have caught whilst in the boot. Flicked the switch and the car started straight away. Someone more knowledgable than me will probably have a more likely solution. There could be a break in the wire from the pump.

With ignition on maybe start looking for +12 volts with a multimeter in the circuits that should supply the fuel pump.

Start at the fuel pump relay where its energised by the ECU. Measure for 12 volts between the blue/purple (+ve) and white/slate (-ve) cables that run from ECU to trigger the pump relay coil. If present check also the main +12 volts from battery on the brown cable that provides supply to main contacts of both fuel pump and main engine relay. Finally you could check feed from relay to inertia switch and fuel pump, white/purple cable. Removing fuel pump relay and identifying relevant pin locations on the relay socket may be the best way to gain access to these points.

Wiring diagram here

EARTH: when you jumped the fuel pump did you check whether the pump had a good earth by just jumping the positive and subsequently testing the positive too. My go too on all electrical issues is first check the earth connections.

Here’s a link to gomog . The Plus8 specific section in the workshop manual has a decent range of info including dedicated sections on the efi systems. You can get a good background to whichever your is (Hotwire probably due to the car age). I only glanced through it so more reading would be your route.
I have a Gems system on my car and in that there is an engine protecting fuel pump cut off that activates if it senses your oil pressure drops too low. I don’t know if the other systems have that as well though. What oil pressure do you get?
https://www.gomog.com/allmorgan/plus8index.html

We got it running and it runs well. Thanks to those with additional ideas to check. The issue was the fuel pump relay, which we replaced with a new bosch relay earlier in the week, but it turned out that new relay was bad too. Reading this forum and several posts and references led us to jumpering the pins in the relay socket, and the pump kicked on. That led us to checking with another new relay, and that fixed the issue. We wouldn't have thought a new bosch relay would be DOA, but read one other post where someone else had the same experience.

Good to read that you solved the problem Scott, and in the process learned more about your Morgan.

With almost every manufacturer of everything seeking to cut costs for many a year now, I guess was is inevitable that quality would suffer. At one time Lucas parts came in for criticism, it is a pity to think Bosch may now be in a similar category. Off-shoring production no doubt has it`s issues, and perhaps lead to knock-off manufacture of low quality items using cheaper internals while copying the exterior appearance as close as possible, which in turn,has potential to create a bad rep for the original brand....?

Fake parts seems to have been quite an issue for some time. Not that I am determining that is why your "new" relay did not operate, just that it seems to be a possibility..?

Thanks for updating, good to see it is sorted. I think I may have a similar issue with the radiator fan relay, which I believe is behind the dash at top of bulkhead. I've substituted with an external one for now, but will remember to have more than one relay, or test by jumping the pins when it comes to it.👍

Seems perhaps wise to carry a spare starter motor relay too, as on some Morgan`s such a failure can cause frustration..though the failure seems likely to be on an intermittent basis initially as opposed to total failure..?