home register FAQ memberlist calendar

Go Back   Turbobricks Forums > Mechanical > maintenance & nonperformance

Reply
 
Thread Tools Display Modes
Old 11-09-2019, 11:10 AM   #1
RickATL
in waaaay over my head
 
RickATL's Avatar
 
Join Date: Jan 2015
Location: Atlanta
Default fuel pump staying on

1993 LH2.4 idle problem that i cant seem to solve.



Replaced the main and in tank pumps. It still idled up and down and would stall sometimes. It also sounded as though the main pump was staying on instead of priming and stopping.



I decided to get a brand new fuel pump relay. I had switched out (8).. no kidding... that i had. Theyre used, but i thought - good.



Upon plugging in new fuel pump relay, the pump turned on?? No key in the ignition, no fuse jumps?? What could be going on?
RickATL is offline   Reply With Quote
Old 11-09-2019, 12:12 PM   #2
cleanflametrap
Board Member
 
cleanflametrap's Avatar
 
Join Date: Sep 2009
Location: near baltimore
Default

How did this start happening?

We should ask our friend from down under: http://forums.turbobricks.com/showthread.php?t=351950
__________________
-Art
cleanflametrap is offline   Reply With Quote
Old 11-09-2019, 03:29 PM   #3
RickATL
in waaaay over my head
 
RickATL's Avatar
 
Join Date: Jan 2015
Location: Atlanta
Default

Quote:
Originally Posted by cleanflametrap View Post
How did this start happening?

We should ask our friend from down under: http://forums.turbobricks.com/showthread.php?t=351950

It never really stopped happening. I THOUGHT it was better after I adjusted the throttle. The original post was titled: 93 244 idle problem after warming up


It went back to idle problems. It was even idling up and down like a minute after starting. I was getting strange readings testing the fuel pump replay by back probing. I' d tell you if I could remember what they were. Thats why I did the fuel pump. Then it sounded as though it was running all the time, so i then did the in tank pump thinking the main pump was running to make up for a problem there. It was still idling up and down after the new pumps, so I decided to try a brand new relay, just in case.



I unplugged the old relay and as soon as I start to plug in the new one, IT SOUNDS LIKE the MAIN pump starts running. The key isn't even in the ignition.



Before changing the fuel pumps, I had tried swapping the ECU with another from a 1993 240 and it didn't make a difference with the idle/stall problems.
RickATL is offline   Reply With Quote
Old 11-09-2019, 03:48 PM   #4
cleanflametrap
Board Member
 
cleanflametrap's Avatar
 
Join Date: Sep 2009
Location: near baltimore
Default

Quote:
Originally Posted by RickATL View Post
...

I unplugged the old relay and as soon as I start to plug in the new one, IT SOUNDS LIKE the MAIN pump starts running. The key isn't even in the ignition. ...
Idle and stall problems can have many different causes, mechanical and electrical, but this behavior of the fuel pump running without the key in spells monkey business. In that post I linked, it was very likely a mod for the pink label failure, but a '93 never had a pink label ECU to give someone a reason to rewire things.

If this concerns you as much as it does me, you probably should return to the probing you were doing on the fuel relay. But, be sure you are in voltage measuring mode (from ground) and not resistance with things powered up. Don't play around grounding or applying power to anything, either, in case you're getting that kind of advice. These folk who tell you to use a "POWER PROBE" don't pass along the importance of knowing how easily they can slip up and damage an expensive ECU. Just measure the voltage at the socket where the wires terminate and make note of what you read with key off, key on, and key on running.

There is absolutely no legitimate reason to hear fuel pumps run or relays click when you plug one in with the key in your pocket.
cleanflametrap is offline   Reply With Quote
Old 11-09-2019, 06:36 PM   #5
ZVOLV
<Master Tech>
 
ZVOLV's Avatar
 
Join Date: Nov 2002
Location: California
Default

Unplug the ECU and see if it stops.
__________________
No Start Thread
ZVOLV is offline   Reply With Quote
Old 11-10-2019, 12:42 AM   #6
RickATL
in waaaay over my head
 
RickATL's Avatar
 
Join Date: Jan 2015
Location: Atlanta
Default

Quote:
Originally Posted by cleanflametrap View Post
Idle and stall problems can have many different causes, mechanical and electrical, but this behavior of the fuel pump running without the key in spells monkey business. In that post I linked, it was very likely a mod for the pink label failure, but a '93 never had a pink label ECU to give someone a reason to rewire things.

If this concerns you as much as it does me, you probably should return to the probing you were doing on the fuel relay. But, be sure you are in voltage measuring mode (from ground) and not resistance with things powered up. Don't play around grounding or applying power to anything, either, in case you're getting that kind of advice. These folk who tell you to use a "POWER PROBE" don't pass along the importance of knowing how easily they can slip up and damage an expensive ECU. Just measure the voltage at the socket where the wires terminate and make note of what you read with key off, key on, and key on running.

There is absolutely no legitimate reason to hear fuel pumps run or relays click when you plug one in with the key in your pocket.
Voltage test showed voltage only at the red wire that goes to the #30 pin of the relay.
12.2 volts with the ignition off
11.8 volts on the I

11.5 volts on the II
RickATL is offline   Reply With Quote
Old 11-10-2019, 02:33 AM   #7
hessam69
Board Member
 
Join Date: Jun 2009
Location: Sydney, Australia
Default

On my car, the fuel pump was running constantly whenever the ignition was on.

I pulled the ECU apart, and found it had been "repaired" by someone who thought jumpering one of the big chips inside the ECU to somewhere with ignition power (full time) was a good idea.

I swapped a working ECU in, now the fuel pump only primes for a second with the key in PII and all is well in the starting and running aspect
hessam69 is offline   Reply With Quote
Old 11-10-2019, 06:05 AM   #8
cleanflametrap
Board Member
 
cleanflametrap's Avatar
 
Join Date: Sep 2009
Location: near baltimore
Default

Quote:
Originally Posted by RickATL View Post
Voltage test showed voltage only at the red wire that goes to the #30 pin of the relay.
12.2 volts with the ignition off
11.8 volts on the I

11.5 volts on the II
That's good. That's normal. No problem...

Now how about the other 5 pins?

cleanflametrap is offline   Reply With Quote
Old 11-10-2019, 12:36 PM   #9
RickATL
in waaaay over my head
 
RickATL's Avatar
 
Join Date: Jan 2015
Location: Atlanta
Default

No voltage on the other 5 with the ignition on I
With the ignition on II i got:
86/2. .34 volts
8/71 .34 volts
85. .34 volts
87/2 0
86/1. 0
RickATL is offline   Reply With Quote
Old 11-10-2019, 01:07 PM   #10
RickATL
in waaaay over my head
 
RickATL's Avatar
 
Join Date: Jan 2015
Location: Atlanta
Default

After checking those voltages, i tried unplugging and then plugging in the ecu as suggested by zvolv. I unplugged it though with the ignition on the II. I know, big mistake.



Now the new fuel pump relay wont start the pumps at all.
I plugged in an old relay, and the pumps start but dont stop. It starts but then stalls almost 10 seconds later.
RickATL is offline   Reply With Quote
Old 11-10-2019, 01:46 PM   #11
RickATL
in waaaay over my head
 
RickATL's Avatar
 
Join Date: Jan 2015
Location: Atlanta
Default

If i put it in gear and go i can keep it running. It is worse in park. The pumps dont stop.
RickATL is offline   Reply With Quote
Old 11-10-2019, 05:37 PM   #12
cleanflametrap
Board Member
 
cleanflametrap's Avatar
 
Join Date: Sep 2009
Location: near baltimore
Default

Have you tried turning any of those parts upside down to see how much water runs out?
cleanflametrap is offline   Reply With Quote
Old 11-10-2019, 11:58 PM   #13
RickATL
in waaaay over my head
 
RickATL's Avatar
 
Join Date: Jan 2015
Location: Atlanta
Default

What about these results though,



No voltage on the other 5 with the ignition on I
With the ignition on II i got:
86/2. .34 volts
8/71 .34 volts
85. .34 volts
87/2 0
86/1. 0
RickATL is offline   Reply With Quote
Old 11-11-2019, 05:38 AM   #14
cleanflametrap
Board Member
 
cleanflametrap's Avatar
 
Join Date: Sep 2009
Location: near baltimore
Default

Quote:
Originally Posted by RickATL View Post
What about these results though,



No voltage on the other 5 with the ignition on I
With the ignition on II i got:
86/2. .34 volts
8/71 .34 volts
85. .34 volts
87/2 0
86/1. 0
They don't make any sense to me, and they're not consistent with a fuel pump running. No sense whatsoever, unless, of course, the electronics are under water (or have been) or the wiring has been modified as was the case in a recent exercise in TB troubleguessing.

How could a correctly wired fuel pump run with zero volts on 87/2?
cleanflametrap is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


All times are GMT -4. The time now is 01:48 AM.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.