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No power to fuel pump. New pump and relay

LH2.4 Install/Conversion. Just 4 wires to make it run

LH2.4 Install/Conversion. Just a few wires to make it run Right click dead links and open in a new window to view pics. Do you want to know how to install Bosch LH2.4 EFI in your Volvo? Fantastic! It's very simple and only takes a few wires. We installed a 1994 B230FT and LH2.4 into a 1984 240...
turbobricks.com turbobricks.com


lh24.jpg
 
Get out a test lamp, not a meter, and do your testing right at the relay 217. If a LH2.4 240 harness was used, the relay should be attached to the ECM bracket by the passenger's right foot.

Key on- one half of the relay gets closed via yellow/solid black. That powers up the fuel injectors.

Cranking--- blue-green pulls the other control circuit to ground, and closes the second half of the relay, which is your pumps.

(sometimes the colors are different for the wires. The small gauge wires are the control circuit wires. The larger gauge wires are the power wires.)

So I would start with confirming power to the injectors. That would confirm that the first half of the relay is working normally.

Then cranking, I would have the relay cover off, and then watch if the second relay contact is closing.


I hope that helps more. Do not use a meter, use a test lamp. A meter can show a "weak" 12v, like ONE strand of wire 12v.

You can also manually pinch the second half of the relay closed and the pumps should run. (assuming the first contact has already closed)


Still got your old relay? Pop the cover off on the bench and you can visually trace which terminals are for the power circuit, control circuit positive/negative, etc. You can play around with closing the contacts and even zip tie them closed if you need to do circuit testing away and dont have the spare hands.
 
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2manyturbos said:
The relay should always have power through the red wire at the relay. Pin 4 at the ECU connector and Pin 5 at the EZK connector should also always have power. When the key is turned to the run position pin 6 of the EZK and pin 15 of the ECU should have power. If you have power to the red wire at the fuel pump/main relay, grounding the blue/green wire should make the fuel pumps run if the relay works. The power out of the relay to the pumps goes through the yellow-red wire and passes through fuse # 4. Check all that and report back what you find.
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So i finally was able to get in there. The red wire at the fuel pump relay harness has only 2.8v. And it has it whether ignition is on or not. This doesnt seem right?
 
bobxyz said:
Go to ozvolvo.org/archive and download the 1977 greenbook and the 1993 greenbook (do a browser <Ctrl-F> search for 1977, 1993). The 1977 shows how the car was originally wired (2 separate main+fuel relays). The 1993 shows how the LH2.4 dual main+fuel relay is wired, but the main fuse is different from a '91 harness.

The recommended way of upgrading to LH2.4 uses just the LH2.4 fuel relay, and bypasses all the old K-Jet stuff. If you look at pg 9 of the '77 greenbook, it shows the 2 separate K-Jet main+fuel relays. Check the driver's footwell to see if these relays are gone - they should be. If not, it will take some tracing to see how LH2.4 was retrofitted.

When you turn the key on, do you hear the main/fuel relay click and then un-click a half-second later?
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There are not relays in the drivers footwell. Just the fuel pump relay along with the ECU in the passenger footwell.

I don't hear any click from the relay when key is on.
 
ZVOLV said:
That is not true on LH.
Click to expand...
ZVOLV said:
Get out a test lamp, not a meter, and do your testing right at the relay 217. If a LH2.4 240 harness was used, the relay should be attached to the ECM bracket by the passenger's right foot.

Key on- one half of the relay gets closed via yellow/solid black. That powers up the fuel injectors.

Cranking--- blue-green pulls the other control circuit to ground, and closes the second half of the relay, which is your pumps.

(sometimes the colors are different for the wires. The small gauge wires are the control circuit wires. The larger gauge wires are the power wires.)

So I would start with confirming power to the injectors. That would confirm that the first half of the relay is working normally.

Then cranking, I would have the relay cover off, and then watch if the second relay contact is closing.


I hope that helps more. Do not use a meter, use a test lamp. A meter can show a "weak" 12v, like ONE strand of wire 12v.

You can also manually pinch the second half of the relay closed and the pumps should run. (assuming the first contact has already closed)


Still got your old relay? Pop the cover off on the bench and you can visually trace which terminals are for the power circuit, control circuit positive/negative, etc. You can play around with closing the contacts and even zip tie them closed if you need to do circuit testing away and dont have the spare hands.
Click to expand...
Thank you for all your advice on this. You mentioned in an earlier reply about spark. Didn't think to check this initially because car was running fine last time I pulled it into my garage. But turns out there is no spark from the ignition coil (though it does seem to have power going in with key on).
 
77volvo242 said:
So i finally was able to get in there. The red wire at the fuel pump relay harness has only 2.8v. And it has it whether ignition is on or not. This doesnt seem right?
Click to expand...
Yeah, that's certainly not right. The relay should have +12V battery voltage at all times on the big red wire. You'll need to trace that wire back to the battery (and fuse). It's part of the LH retrofit so it may not match any wiring diagram. Use a test light, or a voltmeter, with key on and see if you can find where +12V battery becomes only 2.8V.
 
If your car has that 25 A fuse holder that’s where the relay gets its power. Quite often the contacts in the fuse holder are so corroded they won’t pass enough power. They can look fine, yet, have a hard scale coating that acts like a resistor.
 
What about just power on the power wire for the injectors? Lamp between power wire and a know good ground? Key on.

Power at MAF? Key on. Test lamp. Backprobe yellow blue wire. Lampe between yellow blue and ground. Illuminate?
 
ZVOLV said:
What about just power on the power wire for the injectors? Lamp between power wire and a know good ground? Key on.

Power at MAF? Key on. Test lamp. Backprobe yellow blue wire. Lampe between yellow blue and ground. Illuminate?
Click to expand...
Thank you. Need a set of test probes and will report back.
 
2manyturbos said:
If your car has that 25 A fuse holder that’s where the relay gets its power. Quite often the contacts in the fuse holder are so corroded they won’t pass enough power. They can look fine, yet, have a hard scale coating that acts like a resistor.
Click to expand...
This, also, the crank sensor. I just had both fail over a summer of sitting.
 
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