Mk1 with ABF - Totally new fuel system and it STILL wont start! Help!

Evening all,

Been busy so not spent much time on the MK1 however this weekend I tried to start it again having fitted a completely new fuel system incl tank (the old one was weeping on a seam and the breather connection was rotten) all new flex pipes incl breathers etc, new 8mm copper flow and return pipes and new in line pump fitted and re-wired with 17 amp cable and in line 15 amp fuse.


.................


Turned it over this afternoon and it still wont start

Its got a spark (regular and reliable), its got a 6 bar fuel pump from a reservoir fed by a lift pump.

If I use the relay the lift pump runs for a couple of seconds and stops and wont run until the ignition is switched off and left for a few seconds, then when switched on again the lift pump runs for a couple of seconds and stops. The main pump runs when starting the car and turning it over and stops when the ignition is switched off. I have fitted a hidden in-line switch and this tests as fine.

I removed the relay and bridged the terminals and the lift pump runs continuously.
There is fuel getting to the rail (I removed the return pipe and it spat it out)

I did turn it over a while ago with carb cleaner down the TB and it fired so I`m sure its a fuel issue.

1) Possible the main pump isnt pressurising properly (unlikely) - should I invest in a fuel pressure gauge? Anyone got one I can borrow?
2) Possible PRV failure on the rail (unlikely) however will the PRV be affected if the vacuum pipe is faulty? - it looks old and battered but I believe it only raises fuel pressure momenatarily as the throttle opens and vacuum increases?
3) Possible injector trigger failure? I put a voltmeter on each of the 5 terminals and got 0.17V on each with ignition on but I`m not sure what to look for when it is turning over.

I still dont know why the lift pump starts and then stops with the relay in!!

Help!!!!!!!!!!!!
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what pumps do you have a lift pump and a main pump? if so both should run at the same time when the key is turned for 2 seconds if your only hearing the lift pump then that could be your issue

 

When the relay is bridged the lift pump runs continuously and when the ignition is on the main pump runs.

The lift pump must be filling the reservoir as the main pump is pressurising the rail with fuel (but I dont know to what pressure) and is a brand new 6 bar Sytec pump.

I just had another look and seem to recall that the coil triggers the injectors? (I`m running a TCI unit with coil instead of the original coilamp as they are unreliable) Can anyone more knowledgeable than me (Rubjonny ) prompt me again with the correct wiring to the coil although I`m sure its correct.

Also - the engine has no water in it yet as I want to start it for a few seconds before I fill it. I dont think the sender will stop it running if its empty but I may be wrong.

 

you say you have a spark while cranking so id say you have the coil correct

as for the fuel pump if your getting fuel to the rail then thats good are the fuel pipes around the correct way ?

im guessing you have checked all the silly things like plug leads around the right way ect but never hurts to prompt lol

 

Is it on the ABF digifant or an aftermarket system?

Are the spark plugs wet or dry?

When I megasquirted the track car, you could hear a 'tick tick tick' when it fires the injectors. Any sounds from yours?

 

Hi John

You wired the loom for me and I have a thick yellow and red supply you provided that tees off and supplies to both pumps. Both circuits were pre-checked for full voltage, resistance and continuity.

Its got the original (non-immobilised) ECU with the original coil and TCI as per your recommendations but I seem to recall that energising the coil triggers the injectors?

I consider the spark plugs are dry.

PS: I`ve installed the fuel system as per the diagram below but with the lift pump in the tank




Another aspect is that the pump is piped wrongly (Sytec do not include instructions) so there are 12mm and 8mm push fit connectors and I`m positive its the 12mm in from the reservoir and 8mm high pressure out - or am I wrong as I cant see a 12mm out supplied by an 8mm in will work?

Another aspect may be the wiring but the smaller ring post terminal has a (very small) plus on it so I assume power and the other larger ring post terminal doesnt so I assume earth!

 

Hi John

The pumps are wired in parallel from the red/yellow connector you provided so have a common feed.

I`ll check both run with the relay bridged as I can only hear the in-tank pump.

It has a brand new OEM 167

The lift pump certainly primes when the ignition is on but only runs full time when the relay is bridged (I assume therefore that the main pump is the same as I hear it prime but it is near silent when running)

You are correct in that if the ignition is turned on the pumps prime and if it is turned off and on quickly they wont re-prime themselves unless a few seconds is left before trying again.

The ECU clicks when the ignition is turned on and off to the first position before starting it. The ISV also clicks - is this the starter live feed?

I`ll check all pins from the ECU as you suggest and report back and check all wiring (again) from the ECU to the engine loom.

BTW.................if the engine earth below the distributor cap is poor what effect would this have? I seem to remember something about it however I am meticulous in preperation so would be surprised however I might run a dedicated wire back to the battery but I`d be interested to know what it affects.

How do I know if the crank sensor is FUBAR? I have a spare s/h one so if fitted will it generate a signal somewhere I can measure?

 

12mm in and 8mm out sounds right to me - larger connector on the bosch pumps is on the low pressure side.

Assume the ECU has a part number ending in AB? Apologies if this is going over old ground, but worth checking.

As you suggest, I'd start by checking that both pumps are running. You've got a spark, so if it's not a fuel supply issue, that narrows it down to the injector signal for me.

 

does the rev counter move on cranking if not then you dont have a tach signal meaning you wont get power to the injectors or fuel pump relay

 

Thanks chaps.......................for now

Thats a lot to think about, I really do appreciate your time on this.

I`ll have a busy Saturday ahead of me and will methodically go through all the suggestions above and get back to you (hopefully with good news)

Once again, thanks.

 

Hi John

I`m out here in the garage as frustrated as hell.

Both pumps prime briefly and stop when the ignition is turned on. They are wired properly and in parallel.

They both run when cranking and stop a half second after stopping cranking and run 10.6 volts (assumed to be due to the cranking) so its not the pumps.

You fitted a blue/red wire piggy backed from the large red/black pump supply wire that goes to the ECU relay connector block. This is momentarily live as the pump primes and then has no voltage. When cranking the engine it is powered and shows 10.6 volts (assumed low due to the cranking) and goes off when the cranking stops.

I put a continuity tester from the engine earth below the dizzy to the earth cable at the battery and it is continuous with negligible resistance so assume it is ok.

The rev counter jumps when cranking so it is seeing a signal.

I get a big reliable white spark in sequence to each plug so its not the rotor arm or leads when cranking so assume the crank sensor is ok?? Or could I be wrong? I do note that each plug sparks once when the engine is turned off.

The plugs are not wet and dont smell of fuel.

I dont think its a timing issue. I did change the cam belt but rotated it twice and all marks aligned properly.

The ISV definitely clicks - noticeably and audibly.

Note that there is no voltage to (I assume) the positive on the injector plug (the larger red wire of the 5 wires) or any other of the wires when ignition is on and there is no 12 volts when cranking.

It must be the injector trigger signal or lack of power nto the injectors but am now completely stumped! What voltage should I see at the injectors?

Any thoughts?

 

To check the wiring is correct................

ECU relay 53 is wired a follows

Small brown/black to connector pin 6 (relay pin 85)
Two large red to connector pin 8 (relay pin 87)
Blue/red feed from pump supply to connector pin 2 (relay pin 87)
Blue/red jumper from connector pin 2 to connector pin 4 (relay pin 86)

Lambda relay 30 is wired as follows

Red permanent live from fuse board to connector pin 2 (relay pin 30)
Earth on block above fuseboard to connector pin 4 (relay pin 85)
Yellow/black to connector pin 6 (relay pin 86)
Black/white to connector pin 9 (relay pin 86a)
Black from fuseboard D2 to connector pin 8 (relay pin 66)

A 167 relay is in position 2 for the pumps.

**********************

When checking against the ECU plug wiring charts.............

The only brown/black is ECU pin 28 - Lambda sensor relay (pulls low) (k94) Is this in the correct relay as its in the ECU relay?

The yellow/black is ECU pin 23 and designated as going to engine control relay pin 87 however its connected to pin 86. Is this correct?

The black/white is ECU pin 9 and designated as going to engine control relay pin 86a which appears correct.

Sorry for the fuss but I`d appreciate a few pointers, thanks.

 

The yellow/black is ECU pin 23 and designated as going to engine control relay pin 87 however its connected to pin 86. Is this correct?


what relay is this fuel pump by any chance? if so id say thats the issue a wire around the wrong way have you tried putting it on 87?

 

Sounds like a good diagnosis to me. I don't know enough about the modern setup to know how the injector trigger is fired, but I'm sure the other guys commenting on the thread have that bit.

I'm not sure if the trigger for these will be on the power or earth. Have you got a good earth on the injector loom. I think the Megasquirt setup triggers on the earth side, with a constant live. Can't remember for sure though.

 

With a faulty CPS the engine won't turn over. You hear the pumps prime but the spark generated at the coil is sent to earth (at the dizzy iirc). There is an audibly tick from within the bay. If the engine is cranking then you shouldbe able to safely rule out a CPS problem.

 

The ECU earths the injectors I am told so I would have thought you`d get an ignition/ECU live to them all and the ECU would trigger them in sequence.

Its where the power to them comes from I`m stymied at as there is a pin on the ECU that shows a connection to the main red on the injector plug but also all 4 injector wires.

There are two 1.0mm reds connected into the ECU relay pin 87 so I assume its those I need to investigate.

Thanks fore the help (and support)

If you see a large black smoke cloud over North Herts later today then you`ll know I decided to set fire to the bl**dy thing