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Replaced fuel pump relay under dash still no power to fuel pump?

Tiny
BRICKED
  • MEMBER
  • 1990 VOLVO 240
  • 2.3L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 100,000 MILES
The car listed above is a 240 DL. The car was parked for a few months due to a brake caliper leak. After the winter passed, I decided to get to work on it. Replaced battery as it was old. Car cranks but will not start. Do not hear pumps turn on. Replaced fuel pump relay under dash still no power to pumps. Checked and cleaned fuse #4 on driver side fuse box still no power to pumps. Replaced fuse assembly near coil as it was pretty weathered still no power to pumps. With cranking engine, I forced power to pumps using bridge on #4 and #6 fuses and car starts right up but dies once I remove bridge.
Just ordered crank position sensor yesterday and will try that today. Is it a possibility the crank sensor is not sending info to ECU therefore not releasing power to pumps? Or my last option is the ECU not grounding for fuel pumps therefore not sending power to pumps?
I have tried to work my way from least complicated and expensive to most as I was going to replace these at some point anyway.
Any ideas?
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Tuesday, March 7th, 2023 AT 10:16 AM

8 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

If you are able to jump the secondary side of the relay and the pump runs, chances are the primary side is the issue.

If you look below, I attached the directions for testing the fuel pump relay circuit. Take a look through it and let me know if you are comfortable performing them.

Additionally, you may find this link of interest:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Let me know.

Joe

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Wednesday, March 8th, 2023 AT 7:44 PM
Tiny
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Hi Joe,
I got your information but had already tapped into the green and blue wire from the pink label ecu and grounded it with a toggle switch and it started right up but died out in a couple seconds. Sounds like the pumps turn off once it starts. I replaced the crank sensor as the wiring insulation was old and falling apart. Do I just need a new or refurbished ecu or is there something else that could be causing the pumps to shut off once it starts? Also, I checked the self diagnosis system and no codes seem to be saved on computer. How long does it take for computer to save a code?
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Friday, March 10th, 2023 AT 2:44 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

There are different types of codes. Some will set the first time a malfunction is identified. Others take two consecutive failures for it to set.

Are you sure the in-tank fuel, feed pump is working?

Joe
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Friday, March 10th, 2023 AT 10:01 PM
Tiny
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So, I ran some tests on the in-tank pump and couldn't hear it turning on or get an accurate voltage reading so I went ahead and purchased it to install tomorrow. I went ahead and took out the old one today, what a headache only because it seems like it had never been done before. Hoses and flange were caked with soil and rust, it took a good three hours just to loosen the flange with a mallet and flat head as there was no flange tool available at local auto parts stores and there isn't enough room in the opening to work properly. Filter or screen as they call it attached to pump was hanging on by a thread, so it definitely needed to be replaced. I would recommend people go and clean the area periodically to avoid the frustration when the time comes. Fingers crossed for tomorrow.
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Saturday, March 11th, 2023 AT 8:16 PM
Tiny
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Changed out the fuel pump today and got the same results, no start and can't hear the pumps turn on. The only way it will start up is by either grounding the blue/green wire from the relay or bridging #4 and #6 fuses. So, unless there is something else like TPS, MAF or some other sensor I believe my ECU may be at fault.
Going to run it for a while and drive it around to see if the check engine lights up and records a code. Till then, thanks for the help in diagnosis. Let me know if there is anything else you can think of.
Last question, since I grounded from the relay I notice after turning off key the pump will continue on for a couple seconds, is that normal? Thanks.
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Sunday, March 12th, 2023 AT 9:23 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Since I don't have great schematics, I have a question. You indicated it will start if you ground the blue/green wire from the relay. If that is the case, then the issue is either a faulty ground via the connector at the ECM or the ECM is bad and not providing a ground path.

Take a look at the pic below. Does that appear to be what you are looking at on the vehicle? I ask because when I look at the schematic for the 2.3L, I don't see a blue/green wire. When I look at the schematic for the 2.4, I do.

Pic 1 is the 2.3L and pic 2 is the 2.4

Let me know.

Joe

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Sunday, March 12th, 2023 AT 2:31 PM
Tiny
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Hi Joe,

Yes, it is the 2.4 as pictured in diagram 2 with blue/green wire. What I found was after 89' they used the Bosch ecu and made it 2.4. I have conflicting paperwork on mine as the previous owner/seller didn't know and put ink to paper on what they thought or remembered so it took me a while to get that sorted. But the good news is it runs without fail for now. I had always suspected this was the issue but knew I needed to start replacing parts anyway. So, I used this as an excuse to work my way to replacing them. In all its good experience on these old cars as not many mechanics these days will touch them. I will investigate the ECU further and figure out if it's a bad ground or if the ecu is bad it that area. Thanks again.
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Sunday, March 12th, 2023 AT 5:05 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

Thanks for the update. If you can, take a test lamp and attach the alligator clip to the battery positive +. Probe the blue/green wire. The test lamp should remain off until the key is in the on or start position and then turn on.

Let me know if you have a chance to check that.

Take care,

Joe
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Sunday, March 12th, 2023 AT 7:23 PM

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