fuel pump, fuel gauge and horn not working...

[jc_uk]

Hi,

Trying to get my Elan back on the road after a few years in storage.......
Replaced the main beam lamps and also the shabby wheels and tyres with refurbished OZ rims plus new Uniroyal Rainsport 3 tyres.

Couple of problems though, fuel wise......

1. Fuel Pump not working
I put 12v to the pump direct and no noise.
Swapped the pump out for a new Merlin pump - easy once I worked out how to get to the access cover.....
Put 12v to the pump and it works as expected.
Key in ignition and can hear the fuel pump relay, put the fuel pump is not running.
(I'm assuming the relay is OK)
Checks A3 and D2 (hard to get at) fuses and both ok, ie not blown.
No voltage on terminal 3 of the fuel pump relay - I though I saw 12v at this terminal with the old pump in place but not connected.......
Inertia switch is on (down) position......
(I'm assuming the Inertia switch is ok - any easy checks to confirm it is OK, and not part of the problem?)
Need to check the wiring now......

2. Fuel gauge saying empty, but with at least 11l of fuel in the tank
This was the case before and after the new fuel pump.
There is plenty of petrol in the tank but still showing empty on the gauge and light on.
The float etc. looked ok when I changed the pumps over.
I'll probably go and have another look at the float and check it has not filled with petrol or otherwise snagged.
In terms of signal what am I looking for and on which cable/terminal coming out of the fuel tank going to the fuel tank gauge?

3. Horn intermittent working/not working
The horn seems to work, and then not work, but can't explain how/why yet.....
I note that this and the Fuel Pump are both on the D2 fuse.

Thanks for any ideas/suggestions.

Many thanks
JC

[dapinky]

Hi JC,

I'm no expert in tracing/diagnosing anything electrical (or probably just 'anything'), but some things I would look at are:-

Check that the inertia switch is connecting/disconnecting with the plunger - I don't know the pin configuration, but I expect it to be a simple connected-when-down / dissconnected-when-up thingy - so a continuity check between the pins sould show a complete circuit when down, and a broken circuit when up. From reading the electrical manual, it needs a 'pulse' from the ECU when ignition is on to operate the relay, so i would isolate the whole system and try a static 12V feed to the pump relay, then trace my way down the line until i find 0v where there should be some.

For the fuel level, it could be electrical (to the gauge) or mechanical (float stuck). I know that the exact position of the pump assembly is critical to float movement due to the shape of the tank.... if it is a few degrees of rotation out, then the float will catch internally and not move, thus showing 'empty' at all times. May be worth undoing the collar and trying it turned a few degrees in either direction to check that the float actually floats.

If it does, then it is an electrical connection, either at the tank assembly or to the gauge.

If you can follow a circuit diagram, then the 'electrical manual' will help you.

[jc_uk]

Hi again,

Making progress........

Checked the voltages at the inertia switch and re-seated the Fuel Pump relay and now I can hear the pump when trying to start the car, etc.
Car is still not starting, so I next want to make sure the pump is actually building the pressure as well as making a noise.
I fitted a merlin pump and it didn't seem to make as good contact with the pipework as the old original pump......

The fuel gauge is still showing empty.....
I've checked that the float is not full of petrol and it is free to move up and down.
Looking for the test for the signal from the Fuel sender unit so I can test that.......

Horn is still intermittent......

Thanks
JC

[lotusflasherman]

Sounds to me like classic 'not used for a while' syndrome... - open contacts get tarnished, relays get sticky, terminals get verdigris .. etc.

There is no association between horn circuit and fuel pump & gauge circuits so you can treat those as separate problems, assuming your battery is good..

Horn:
Horn has permanent feed to Horn relay through 15A Fuse A1 ( top left fuse in fusebox in passenger footwell forward of door post) - pull it in and out a few times to clean it up.
The Horn relay is behind the Voltmeter, mounted on the chassis cross tube on it's own and slightly away from 3 others - remove the instrument pod cover for access. Pull relay out and re-seat it.
Try Horn and if it doesn't work can you hear the relay clicking?
The Horn relay coil is fed from 3A Fuse A12 which also feeds other relays and keeps the digital clock going - if the clock is going that will be OK.
The Horn Push on the steering wheel provides an earth for the relay coil (to pull in the main contact). Contacts may be tarnished. Use an 'earth wire' to dab the live feed to operate the relay...
When the relay pulls in it feeds the 2 horns which are earthed to chassis .. somewhere. Horns have spade connectors and sit low down near the oil cooler and can get mucky so check those and earths.
Horn has internal contacts and iron rod attached to diaphragm that is pulled in by a coil, and contacts open, so springs out closing contacts, pulls in again etc, etc to vibrate diaphragm. These can corrode internally ...
Put 12V directly onto horn terminals to prove they are OK.. (earplugs may be an idea .. )

Fuel:
Looks like you've checked most of the obvious stuff... Fuel Senders usually return a low resistance to send the gauge full scale to FULL and higher resistances to show lower fuel levels and Empty. An open circuit would be a very high resistance that would show Empty and trigger the Fuel Low Warning Light so you may not be getting communication between the sender and the gauge. Be aware that the Temperature Gauge, Fuel Gauge and Low Fuel Warning Module are all 10V devices supplied through a Voltage Stabilizer, (that's to give consistent readings whether supplied from a low battery or full alternator volts) so another little complication when testing. I'd say if your Fuel Warning Light is coming on your Voltage Stabilizer is probably OK... (Where's Pete? )

[jc_uk]

Hi,

Thanks for the info.

Horn:
I'll look into that.

Fuel Sender:
Fuel gauge at zero and warning lamp on.
How/where do I check the resistance please?
Can I do this at the tank connector with the sender in the tank, with my ohm/multi meter?
If so which pins please?
Which pin can I earth to drive the full signal to the gauge to test the connectivity from tank to gauge?

Fuel Pump:
Any simple way to test/tell that the new Merlin fuel pump is installed and pumping the fuel please?
It is making all the right noises, but when I de-pressure the system and take the fuel pipes off I'm not getting very much fuel coming out of the pipes......... I would expect more if it was pressurised before being released.......

Many thanks
JC

[jc_uk]

Hi again,

Does anyone have a diagram that shows how the fuel pump fits in with the pipes and various rubber parts please, ie part ACDelco 25004553

Many thanks

JC

[lotusflasherman]

Fuel pump should have 12V on the White Green.
The Sender is Green Black. Pull spade off and measure terminal resistance to earth. Connect Green Black to earth and see what the Fuel Gauge does...

Picture is worth a thousand words...

fuel sender.JPG

fuel pump.JPG

[Simon_P]

Do you have an alarm or immobiliser?

They often work by cutting the fuel and sounding the horn.

[jc_uk]

Hi,

Only the factory fitted one and I don't think I am getting a problem with that (yet).

Anyone have a drawing or a picture of the fuel pump with the rubber part rubber i.e. part ACDelco 25004553 fitted.
I think I missed that off when I fitted the Merlin pump, hence lack of pressure.......
Something else to try next weekend.....
Along with testing the fuel sender circuit and the horn circuit.......

I've forgotten the feeling of Elan ownership over the past few years.......
I've had mine from almost new and now restarting at approx. 89k miles, complete with refurb's wheels, and new tyres, main beams and hood.... once I've got it running again....
Then onto the suspension (likely) and door rebuilds (very likely).....

Many thanks

John

[clemo]

LFM said :- There is no association between horn circuit and fuel pump & gauge circuits so you can treat those as separate problems, assuming your battery is good..


Don't treat the 3 problems as 1 .
It is confusing the issue .
Horn could be as simple as naff contacts being the horn pusher ... its a copper ring with 2 terminals .

you know you have fuel in it ( i guess decent fresh fuel ) yes .

As for the other
Are you getting a spark ? is it cranking and attempting to fire up , more than just a fuel pump noise , a proper - you know , common fire up you bugger noises .

[jc_uk]

Hi again,

After a bit of break I'm back at trying to get my Elan going......

The issues with the horn seems to have sorted itself out and is working again,

I still can't get the new fuel pump working correctly........ nor the fuel gauge.....

Have tried earthing the green sender cable in the harness and the fuel gauge goes to full, so wiring harness back to the gauge is find and the issue is probably with the potentiometer or other wiring in the pump/sender assembly..... Leave that for now until I get the fuel pump working and the elan started up....

Attached a few photos of the new (Merlin) fuel pump in the assembly....

With the assembly in the tank or outside the pump makes a noise like it is working when 12v is applied to the red terminal via the connector at the top of the assembly.

The pump doesn't appear to build any pressure in the fuel pipes and the fuel connectors can be disconnected without any fuel leakage.
Have I got the assembly back together in the correct order - I think I have...
Is the 12v supply the right way round to the Merlin pump?
Anything else I may have missed?

Any easy ways to test the pump is working outside of the tank other than the noise?

Many thanks

JC

[Brit-Car-Nut]

Don't be insulted, but is there a chance the wires are on the pump backward? Are you sure the positive wire is going to the positive connection? If they are reversed, the pump will run backward...

Did you replace the pulsator? Any chance it is clogged? Your pump looks awfully tight in the space. When I did mine I found a pump that was the same length as the original.
The rubber connecting hose isn't pinched/crimped, is it?

pump.jpg

The pump will pump water, so you could grab a bucket, put in enough water to be below the pickup and test it with a jumper battery or similar and a pair of wires. Then you can see what is and isn't working.

Just dry out the pump before putting it back in the petrol.