Show full size 924Board.org
Discussion Forum of 924.org
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
 Technical FAQ924 FAQ (Technical)   Technical924 Technical Section   Jump to 924.org924.org   Jump to PCA 924 Registry924 Registry

Testing Fuel Pump Relay
Goto page 1, 2, 3  Next
 
Post new topic   Reply to topic    924Board.org Forum Index -> General Discussions
View previous topic :: View next topic  
Author Message
winddude  



Joined: 15 Jan 2020
Posts: 41
Location: Vancouver Island

PostPosted: Mon Apr 06, 2020 8:34 am    Post subject: Testing Fuel Pump Relay Reply with quote

I'm trying to diagnose an electrical issue with my fuel pump relay, everything seems to test correctly at the relay board, and I can jump the pump and they both run.

So I thought i'd narrowed it down to a bad relay. I've order a replacement, it didn't work, so I assumed it was faulty, same with the 2nd replacement. However they both test the same.

Quote:
Some quick tests on my spare relay PN 433 906 059 for the '79 924
(Hopefully not both of your relays are bad) show the following:
Measure continuity between ...
30 Battery and 31 Ground -- infinite
31 Ground and 87 Pump -- infinite
31 Ground and 15 Ignition Switch -- ~15 KOhm
15 Ignition Switch and 1 Ignition Coil -- ~35 KOhm
15 Ignition Switch and 87 Pump -- infinite
87 Pump and 30 Battery -- infinite
87 Pump and 1 Ignition Coil --infinite
1 Ignition Coil and 30 Battery -- ~20 KOhm

above from http://www.924board.org/viewtopic.php?t=39601&sid=a230175db721ed826491058744468ed4

Both of the new relays test the same, but don't meet the above. On the final test '1 Ignition Coil and 30 Battery -- ~20 KOhm' I get an infinite circuit.

Can anyone confirm what is actually correct for the relay? I'm stuck, and everything else seems to be testing correctly according to the Haynes manual.
Back to top
View user's profile Send private message
dogleg5  



Joined: 01 Apr 2020
Posts: 29
Location: No longer with us

PostPosted: Sun Apr 12, 2020 12:13 am    Post subject: Reply with quote

So, what is going on exactly? If you can get the pumps to run via jumper wire are they not running at all with a relay in place or is the car just not starting? Did this come on suddenly? You might have to look at the ignition switch as being the culprit here. When you by pass the relay you're by passing the ignition circuit also. When I jumper mine the pump starts running immediately as long as the battery is connected. This just my guess. Can you start the car with the jumper wire in place?
Back to top
View user's profile Send private message
winddude  



Joined: 15 Jan 2020
Posts: 41
Location: Vancouver Island

PostPosted: Tue May 05, 2020 4:22 am    Post subject: Reply with quote

Yes It starts with the relay jumped. It did start relatively suddenly, although the car is new to me. I had it sitting for about a month, while repairing the dash, after the pumps will no longer run without the relay jumped.

I've gone through the haynes to try and trouble shoot any issues at the relay connector, and everything checks out. :s

more details are here: http://www.924board.org/viewtopic.php?p=400292
Back to top
View user's profile Send private message
dogleg5  



Joined: 01 Apr 2020
Posts: 29
Location: No longer with us

PostPosted: Tue May 05, 2020 7:59 am    Post subject: Reply with quote

Well that's strange. If it starts and runs when you bypass the relay then it should start and run with a new relay which you say it doesn't.
So I don't know what to tell you.
Back to top
View user's profile Send private message
Fasteddie313  



Joined: 29 Sep 2013
Posts: 1934
Location: MI

PostPosted: Tue May 05, 2020 9:10 am    Post subject: Reply with quote

What is the car?

safety fuel cut circuit might not be operating correctly, and that circuit depends on year and model...
_________________
80 Turbo - Slightly Modified
Back to top
View user's profile Send private message Yahoo Messenger
winddude  



Joined: 15 Jan 2020
Posts: 41
Location: Vancouver Island

PostPosted: Tue May 05, 2020 1:00 pm    Post subject: Reply with quote

Fasteddie313 wrote:
What is the car?

safety fuel cut circuit might not be operating correctly, and that circuit depends on year and model...


1980 924 N/A manual
Back to top
View user's profile Send private message
winddude  



Joined: 15 Jan 2020
Posts: 41
Location: Vancouver Island

PostPosted: Tue May 05, 2020 1:29 pm    Post subject: Reply with quote

Looking at the wiring diagram, what is 'IV 19'?

Back to top
View user's profile Send private message
924RACR  



Joined: 29 Jul 2001
Posts: 8298
Location: Royal Oak, MI, USA

PostPosted: Tue May 05, 2020 8:55 pm    Post subject: Reply with quote

Circuit track 19 on circuit diagram page "IV" (4).

IIRC in this case it goes to the tach.

I can't see a statement in there that you've verified that you have continuity between fuel pump relay terminal 1, the coil, and the tach - these are all on the same circuit, the tach signal is needed for the relay to run as a crash precaution.
_________________
Vaughan Scott
Webmeister
'79 924 #77 ITB racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype
Back to top
View user's profile Send private message Send e-mail Visit poster's website
winddude  



Joined: 15 Jan 2020
Posts: 41
Location: Vancouver Island

PostPosted: Wed May 06, 2020 2:00 am    Post subject: Reply with quote

Tach works, I'll double check for continuity between coil and terminal 1 on the relay board. But I'm not even getting the pump running to prime. I was before.
Back to top
View user's profile Send private message
winddude  



Joined: 15 Jan 2020
Posts: 41
Location: Vancouver Island

PostPosted: Wed May 06, 2020 2:39 am    Post subject: Reply with quote

Yes, I have continuity between 1 on the fuel pump relay board and 1 on the coil.

Also on the fuel pump board, with the ignition on:
9v from ignition - 15
12v from battery - 30
1.1v from coil - 1

While cranking:
9v from ignition - 15
12v from battery - 30
2-3v from coil - 1
Back to top
View user's profile Send private message
D Hook  



Joined: 02 Nov 2002
Posts: 3109
Location: Omaha, NE

PostPosted: Wed May 06, 2020 3:32 am    Post subject: Reply with quote

This is kind of a long shot but thought I'd mention it. I had a problem with a relay once (don't recall which one) that wasn't seemed to be working. Found out I had actually pushed the spade connector out of the back of the fuse panel where it plugged into so everytime I'd insert the relay, the connector would get pushed back and not make a good connection.

Like I said, long shot but might be worth checking.
_________________
'80 924 n/a SOLD
Back to top
View user's profile Send private message Send e-mail
winddude  



Joined: 15 Jan 2020
Posts: 41
Location: Vancouver Island

PostPosted: Wed May 06, 2020 3:48 am    Post subject: Reply with quote

Look like the terminals are all good. New KAE relay doesn't push in all the way maybe :s

I'm stumped... my relay went bad, and 2 bad KAE relays in a row from the parts store...
Back to top
View user's profile Send private message
winddude  



Joined: 15 Jan 2020
Posts: 41
Location: Vancouver Island

PostPosted: Wed May 06, 2020 3:58 am    Post subject: Reply with quote

I've wired a switch up between 87 and 30.

It seems to run a little rougher than it did before, until I switch the pump off, goes up to about 1200rpm, smooths out for a couple seconds before dying.

Maybe related? coil, alternator, short somewhere else in the electrical? Thoughts?
Back to top
View user's profile Send private message
winddude  



Joined: 15 Jan 2020
Posts: 41
Location: Vancouver Island

PostPosted: Wed May 06, 2020 5:10 am    Post subject: testing coil Reply with quote

While testing my coil, pg 128 in the Hyanes talks about a primary resistance, and secondary restince. The primary resistance is supposed to be between terminal 1 & 15, do they mean the connections that attach to the coil? And secondary resistance, terminal 1 and 15 of the coil.



I get the opposite of what's described:
1ohm across coil terminals 1 and 15.
9.8kohms across the connections that go to the coil.

I'm not sure if I've tested wrong, the haynes is wrong, or my coil and something else is wrong.


Last edited by winddude on Wed May 06, 2020 5:53 am; edited 2 times in total
Back to top
View user's profile Send private message
dogleg5  



Joined: 01 Apr 2020
Posts: 29
Location: No longer with us

PostPosted: Wed May 06, 2020 5:10 am    Post subject: Reply with quote

I suck when it comes to figuring out electrical stuff. When I bought my 82 the pump wouldn't run so the easiest thing for me to do was look to the relay as the fuses were all good. Before buying a new relay or trying to rig up jumper wires in the panel, I opened the relay I had and wedged the contacts together with a short piece of straw from a WD 40 can. Flattened it as much as I could and wedged it in there to hold the contacts together. Pump ran all the time obviously but, it told me it was the relay. (I keep this as my test/emergency relay in the glovebox) If you still have either of the two new relays you bought, try that. If it runs you have another bad relay UNLESS something is causing the relays to malfunction. If that were the case I would think that the jumper wire setup you have would start to get hot and melt wiring. Again, I suck at electrical stuff.
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    924Board.org Forum Index -> General Discussions All times are GMT + 10 Hours
Goto page 1, 2, 3  Next
Page 1 of 3

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group