Have a i shorted [and destroyed] my fuel pump?

Had problems with engine cutting out (see my post history over last 12 months) or just failing to start when engine hot but not when cold. Now MGF 2001 wont start at all.

Tried hard wiring the positive terminal of the battery to the purple-white wire going into the fuel assembly. Read about this trick from post #24 of this thread. Got a spark so assumed I got a closed/complete circuit. Tried cranking and still would crank but would not start. Attached a photo of the hard wiring job.

Took the fuel out pipe off and tried priming and no fuel comes out (none while cranking either). I think I've either:

A: Destroyed my fuel pump by connecting to the wrong wire/circuit. :oops:

OR

B: The fuel pump has been slowly dying (why i've had car trouble this whole time)

Let me know which is which? Thanks guys!

Well I think that you might have diagnosed the problem and it really does not need a speculative answer to A or B. All these cars( TFs included ) are getting well past their sell by date now . Also the pumps have to deal with increasing amounts of inactivity if they are cars that run only part of the year. Moisture drawn into the fuel system causes all manner of issues with pumps as the fuel degrades. As long as you have checked the basics ie relays ,fuses , poor wiring / corrosion, bad earth's , fuel filter, I think you might have saved a call to the scrap man.
Fingers ,toes and eyes crossed !
John.

A failing fuel pump can cause problems on and off until it dies once and for all, it happened to me the damned thing would only play up when I wasn't able to do anything about it but when I had tools etc availble it would work perfectly, I wasn't able to properly diagnose the problem until it finally shit itself.
In fact my fuel pump has shit itself again, this time due to a bad dose of dirty fuel.
has the car being sitting for long? Modern fuel doesn't keep well since they took the good clean wholesome lead out of it!
It gets a nasty pong about it and wont burn properly, even when you flick a match into it wont go off with a woof! it wont even evaporate like fresh fuel does.

sworkscooper wrote:

Well I think that you might have diagnosed the problem and it really does not need a speculative answer to A or B.

In this rather odd case I do need a speculative answer. I've no money to maintain and would like to move it either to the scrap heap or another buyer.

I.e. if its A I've shorted it out (by linking the positive terminal to the purple/white wire) wire and the original issue is something else (and the fuel pump is an extra fix) then i'll scrap it.

If its B then its just a case of the fuel pump slowly dying then I'll get a replacement then I'll get it MOT'd. Then sold.

@Cobber The car has been run (for 30 minutes) every 2 weeks for the entire time its been stored until it fully died last month. It got progressively worse to the point where it would die when you tried to pull away but would happily idle. No stuttering or misfires for the duration. I've kept it on life support until the weather warmed up and now im trying to fix it.

White/purple is the correct wire.


Check the fuse 23.

The pump works on battery voltage so the bypass you have done just provided it with battery voltage which it is designed to run on. Did it make any positive difference starting the car with the bypass wire in place ?

Thanks for confirming that David. I'm glad I correctly read the diagram.

Checked continuity across fuse 23 and its golden. Getting 12v on the purple line so i'm assuming this is a component [fuel pump] problem not a power/wiring problem. Ordering a new £50 fuel pump off the ebay.

@Notanumber My post is very confusing and could use some more detail: The cars been pumping fuel to the engine. Last month I'd seen it pump fuel into a jug and had the injectors out to check spray pattern. What I didn't have was a fuel pressure gauge which [and this is a theory] would have told me the fuel pump was slowly dying [not providing enough pressure]. I dismissed the pump as an issue cuz I found it hard to believe as pump was only 2 years old BUT I did have a faulty alternator in the summer which caused odd behavior with the lights and radio. Maybe that's caused its death?

Its good to hear from Cobber that a failing fuel pump can cause all sorts of problems. I'd, again, dismissed it as an issue thinking: "its either working or broken as its only a motor". I now guess the commutator could have burned out a bit but not completely causing a slowly dying pump leading to lower and lower fuel pressure .

Anyway, currently the car doesn't start (only cranks with sparks) and that's definitely partly or fully caused by no fuel going from the fuel pump. This post was to establish if its just the fuel pump or it could be multiple things. I'm going with a replacement pump and seeing what happens.

You guys, as always, have been stupid helpful and patient and appreciate that tremendously.

The golden rule is ALWAYS suspect the new part!

Fingers crossed for the quick arrival of the new fuel pump

Let us hope this another car snatched from the withering hand of the scrap man.
My tf was a “take it away tomorrow or the scrap man comes the day after”
That was such a great car & only went when I needed a car with seats for the grandkids.
M

Replaced fuel pump. Started stopped and started it a few times without issue. Ran it around the bypass a few times and thought "haha, its fixed". Took it to the MOT centre and they got it on the ramps and after 25 minutes it shut itself off during the emissions test. Started again after a 5 minute wait but they said they would have to rebook the test again. I went and got it back and tested it for myself. Sure enough I can drive it like a lunatic, no problem, but if i leave it idle for 25 minutes it shuts itself down with no audible or visual reason (Coolantneedle just below halfway, Oil Temp barely above minimum lowest). Just turns itself off like the keys been turned (lights on dash still stay on).

After it did this I tried starting it and running it again but after another 25 minutes the expansion filler cap did the ol' James Bond smoke screen and created a cloud of steam. So I shut it off. Expansion tank ended up empty.

I'm gonna bleed the system tomorrow but I think its something more serious than coolant. If its shutting down suddenly so i'm thinking a piston is deforming with the heat and causing the engine to seize. Might be what killed the fuel pump that had only done 3000 miles before dying. Cant be head gasket as its been done already, not seeing the forbidden chocolate milkshake in the coolant and the compression tester put every cyclinder at exactly the same pressure as the other so the cylinder head cant have moved.

Will try bleeding it tomorrow but if it cant idle for longer than 20 minutes then i'll never got it through MOT and i'll have to scrap it. I'm unbelievably depressed over what is just a hunk of metal!

P.S. I didnt even know how to change a tyre when I replaced my Hyundai with an MGF. I know SO SO SO much about the mechanical aspect of cars and the joys of driving thanks to it. Going back to a tame, reliable Japanese hatchback is gonna be heartbreaking.

P.P.S if anything I said sounds wrong it probably is. I'm entirely self taught from googling. Please correct me

Does anything show up on a diagnostic at all when the engine shuts down ?