1989 3.5 V8 EFI question - fuel pump and sequence of fuel delivery

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Jerry de Frates

Jerry de Frates

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Location
Ireland
Please can someone advise me on the sequence of fuel delivery, the fuel pump is running all the time before I start the engine and is really loud, sounds like an old bendix top loader washing machine! Looking around I think that it should come on when you turn the key to the second position, build up pressure the pump, run for a fixed time (about a second) each time you switch the ignition on, pressurise the fuel rail and then turn off until you turn the key to the third position to start the vehicle. There are two relays under the drivers seat, (Bosch 0 332 014 113) and a "big red one" I suspect that this is a diode pack but don't know and would l like to. I swapped the two bosch relays over and didn't make any difference, pump still runs all the time. I pinched the rubber fuel pipe / flow before it connects to the injector rail, pump does less sloshing about and noise level increases as the pressure on the rubber pipe is increased, but it never stops pumping (ignition switch in second position). My questions are: should it stop as pressure increases, if so what controls the relay to stop it?, it's driving me nuts!
Many Thanks, Jerry
 

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Your photo suggests you have a flapper air flow meter & the 4CU ecu. Same as mine.
If that's the case the pump should only run when the pump relay and/or the starter motor circuits are engaged.

Once started & the key released the flap in the airflow meter will be held slightly open by the intake of air & the pump will run continuously, unused fuel going back to the tank. If the flap is closed fully (e.g engine stalled) the pump should stop.
With the ignition switched on - not to the 'starter motor turning' position - pushing the flap open gently should cause the pump to run, something I've used on mine to test the fuel hoses for leaks after replacing them. Worth having a look at the flap & ensuring it's fully closed - esp if you've had a flashback (are you on LPG as well?) which could damage the flap causing it to stick.

Other than that I'd say you have an electrical fault causing the pump relay to be on all the time. Unfortunately electrickery isn't my strong suit & either the relay is stuck closed or it has a permanently on feed to it's switch side & finding that is going to be the key.
There is a list of electrical tests in the factory manual -SRR660ENWM, a paper manual not the RAVE disc - but I don't know if they're available on line either on a LR website or to download.
There are 4 fuel related relays. The big red one is the 'current Steering diode pack'. If these three are oriented the same as mine the one to its left as you view from the front of them is the 'main relay' and the one to its right is the 'fuel pump relay'. The 4th is in the engine bay close to the afm & is the 'over-run fuel shut off relay'.

That's as much as I know!
 
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in haynes workshop manual , it states" the pump is wired in such a way that it is only energised when the ignition is switched on and the engine is running, or when the starter motor is cranking. An inertia switch , in series with the pump, stops the pump operating in case of an accident"
 
The Haynes manual - I've got the older one which goes into much more detail than newer ones - does have a fair bit on the flapper system in it's 'supplement' section, much of it being a straight lift from the factory manual, but doesn't cover the electrical tests simply advising that it needs specialist equipment & should be taken to a dealer. I'd suggest if you do finish up going that route a good older indy is going to have more knowledge about the workings of 30+ year old RRs :)
 
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Ratae said:
Your photo suggests you have a flapper air flow meter & the 4CU ecu. Same as mine.
If that's the case the pump should only run when the pump relay and/or the starter motor circuits are engaged.

Once started & the key released the flap in the airflow meter will be held slightly open by the intake of air & the pump will run continuously, unused fuel going back to the tank. If the flap is closed fully (e.g engine stalled) the pump should stop.
With the ignition switched on - not to the 'starter motor turning' position - pushing the flap open gently should cause the pump to run, something I've used on mine to test the fuel hoses for leaks after replacing them. Worth having a look at the flap & ensuring it's fully closed - esp if you've had a flashback (are you on LPG as well?) which could damage the flap causing it to stick.

Other than that I'd say you have an electrical fault causing the pump relay to be on all the time. Unfortunately electrickery isn't my strong suit & either the relay is stuck closed or it has a permanently on feed to it's switch side & finding that is going to be the key.
There is a list of electrical tests in the factory manual -SRR660ENWM, a paper manual not the RAVE disc - but I don't know if they're available on line either on a LR website or to download.
There are 4 fuel related relays. The big red one is the 'current Steering diode pack'. If these three are oriented the same as mine the one to its left as you view from the front of them is the 'main relay' and the one to its right is the 'fuel pump relay'. The 4th is in the engine bay close to the afm & is the 'over-run fuel shut off relay'.

That's as much as I know!
Click to expand...
Thanks Ratae,

Yes, I have flapper air flow meter & the 4CU ecu. when I turn the ignition switch to the first position nothing happens, when I turn it to the second position the pump kicks in but it never stops in that position, my impression is that it should stop once the system is pressurised and before I actually try and start it.

It sound like your relays and current steering diode pack are orientated the same as mine and the fourth relay is also in the same place.

I have the factory manual but I needed a baseline to start somewhere, I will check if the flap is closing properly, I'm not on LPG as well, If that doesn't work I'll have to work through the wiring with a meter when I get a chance.

I'll let you know if the outcome.
Many Thanks
Jerry
 
Jerry de Frates said:
Thanks Ratae,

Yes, I have flapper air flow meter & the 4CU ecu. when I turn the ignition switch to the first position nothing happens, when I turn it to the second position the pump kicks in but it never stops in that position, my impression is that it should stop once the system is pressurised and before I actually try and start it.

It sound like your relays and current steering diode pack are orientated the same as mine and the fourth relay is also in the same place.

I have the factory manual but I needed a baseline to start somewhere, I will check if the flap is closing properly, I'm not on LPG as well, If that doesn't work I'll have to work through the wiring with a meter when I get a chance.

I'll let you know if the outcome.
Many Thanks
Jerry
Click to expand...

Forgot to attach the scan from the workshop manual
 

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al-one-arm said:
in haynes workshop manual , it states" the pump is wired in such a way that it is only energised when the ignition is switched on and the engine is running, or when the starter motor is cranking. An inertia switch , in series with the pump, stops the pump operating in case of an accident"
Click to expand...
Thanks al-one-arm, I have posted what I have in the workshop manual, I desperately needed it in words of one syllable before I rip it apart, the more clarification I can get the less time I will need to spend remembering how to use the multi-meter!
 
Ratae said:
The pump running & then stopping is the hotwire system:
"Fuel Pressure
When the ignition is turned on for the first time without starting the engine, the fuel pump will be heard to run for around two seconds and then stop. It will only run again when the engine is started, or if the ignition is switched off and on again."
http://www.actproducts.co.uk/2011/lucas-14cux-fuel-injection-system-–-installation-and-diagnostic-notes/
Click to expand...
Thanks Ratae
I'll find a suitable pressure gauge before i start to rip the electrics assunder!
 
The flapper doesn't work the same way. As I said earlier, if I have the ignition on (as in warning lights on & in the position it would be in normal driving) unless I physically push the flap partially open the pump doesn't run. As long as I hold it open the pump runs. As soon as I release it the pump stops.

I don't think your problem is pressure.
The fuel pump is receiving power when it shouldn't be & that makes me think the issue is the switching of the relay.
Probably teaching granny to suck eggs & I apologise if I am but a relay is just an electrically operated switch - the fuel pump one being NO (normally open). No need to go past 1.03 in this:


I relayed my headlights a few years ago to take the load off the column dip/main switch as the type used on mine have a reputation for overheating & melting the contacts. Not had one fail since.
 
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I've never tried turning the ignition key to the crank position - which is the other occasion when the relay should also switch on & run the pump - with the starter motor disconnected to check if the pump runs.
I don't know how it's wired together & suspect if there was a fault then your starter motor would be running all the time anyway so I'm just thinking aloud but could the ignition switch be faulty?
Does the pump stop if you pull its fuse?
 
Ratae said:
I've never tried turning the ignition key to the crank position - which is the other occasion when the relay should also switch on & run the pump - with the starter motor disconnected to check if the pump runs.
I don't know how it's wired together & suspect if there was a fault then your starter motor would be running all the time anyway so I'm just thinking aloud but could the ignition switch be faulty?
Does the pump stop if you pull its fuse?
Click to expand...


I will check out the flap first, then pull the fuse, if that doesn't change anything I will get stuck in to the wiring and the ignition switch, Kev12 has also made a point "Worth checking a PO hasnt done a "mod" to the pump wiring?", something that I hadn't even considered.
 
From memory the flapper moves a wiper onto a conductive track to switch the pump..........and the wiper tip and/or track can wear out leaving a bad connection, thus stopping the pump.

So a modification which bypasses the flapper switch would be a logical step to overcome this fault, and then the pump would run whenever the ignition is on?

Pete
 
Yes. Good points.
I had an issue where the pump ran when it felt like it which turned out to be corrosion in the live wire to the connection on the wiring harness that the pump plugs into & I connected a spare battery direct to the pump to prove the pump was good & to get me out of the sh1t.
As the pump simply circulates fuel to the injectors & back to the tank again an ignition switched live would make sense if there is an issue with the afm.
My LPG is manually switched so it shuts the injectors off but the pump still circulates fuel whilst the engine is running (so it's still controlled by the afm) so switch over on the move is instant.
Risk I could see is if the engine has stopped & the pump continues to feed petrol at high pressure which could be problematic in an accident with damaged fuel lines.
 
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