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High Humidity >>> Drivability Issues (SOLVED)

PromiseRing said:
Alright guys I think I know why the 740 would not start sometimes. Radio suppression relay. I can feel it click even when it doesn?t start. Swapped it with the fan relay and it started. Swapped it back just to make sure and it wouldn?t start. So the problem follows the relay. Not really sure why it wouldn?t work since it?s clicking and the connector is all clean:e-shrug:
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It don't work because the relay don't do.
 
Lando said:
It don't work because the relay don't do.
Click to expand...

Here?s the fun part..another no start this morning with the ?good? relay. Swap in bad relay, still no start, swap *back in* good relay...starts. I feel both relays click like they should too.

Maybe I will cut and re crimp new bullet connectors and buy a brand new relay.
 
Redwood Chair said:
Keep parts cannoning it with 25+ YO used junk.
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I haven?t fired the parts cannon at all what so ever. Lol I simply swapped the fan relay for the RSR.

Anyone know where I can fine the bullet connectors (female) and then the insulators that surround them in the connector? I assume Dave Barton has them but wasn?t seeing exactly what I needed I don?t think.
 
PromiseRing said:
Here?s the fun part..another no start this morning with the ?good? relay. Swap in bad relay, still no start, swap *back in* good relay...starts. I feel both relays click like they should too.

Maybe I will cut and re crimp new bullet connectors and buy a brand new relay.
Click to expand...

If you're going to all that trouble to replace terminals and the relay why not replace with a standard Bosch 4 terminal relay. Spade connectors instead of hard to obtain bullet connectors.
 
lummert said:
If you're going to all that trouble to replace terminals and the relay why not replace with a standard Bosch 4 terminal relay. Spade connectors instead of hard to obtain bullet connectors.
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This is a great idea actually, not sure why I didn?t think of that. I assumed that the relay needed to be something specific rather than a standard 4 post relay. No idea on how much current it would need to be rated for, or which wires would go where though:lol:
 
Someone confirm this wiring diagram please. If this is correct, it looks like I can just install a normal relay in place of the OE RSR. It will save money not having to replace 8 bullet connectors. Also, I think I need to check the integrity of the ground for the RSR. The odds of both relays intermittently ?failing? even while clicking is very low. I?d imagine this indicates some type of intermittent ground or power issue.
http://www.240turbo.com/relay1323592diagram.jpg
 
If both relays are original then there is a good chance they’ve succumbed to solder cracking due to the bad heatwave soldering job that many Volvo relays recieved. I haven’t cracked open my original relays yet but I got two new KAE relays that are working just fine for now.
 
When it's dead, does it have spark? Does it have fuel injector pulse?
Do you have a noid light or a test light?
 
ZVOLV said:
When it's dead, does it have spark? Does it have fuel injector pulse?
Do you have a noid light or a test light?
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That?s where even more fun begins. I saw a healthy spark spark from coil>coil wire during the no start. So I know for sure I?m getting spark to the cap. Didn?t have tools with me so I couldn?t pull plugs and check for a healthy spark.

Rented a noid light, saw it somewhat flash intermittently while cranking. Got tools, pulled plugs after 5 seconds of straight cranking, they were bone dry. Checked for spark and it looked weak but could have been a poor ground. AFAIK the RSR has nothing to do with spark on a 1990 NA car. So this leads me to believe it was getting some (maybe weak, I could be wrong) spark but no fuel. I think the noid light intermittency is indicative of a bad/failing RSR or RSR connection. It was likely not enough current to open the injectors. I?m 99.99999% sure the fuel is getting to the rail at a healthy pressure. The car has a NEW in tank pump, filter, and transfer hose, as well as a new/used very healthy main pump and filter. Also tried 2 different fuel pressure regulators.

I have 2 new 4 pin relays with premade connectors coming in the mail tomorrow or Wednesday. I will check resistance between the ground wire for RSR, and the negative battery post. I will do the same with the positive wire and positive post. As well as give them the wiggle test. Any change in continuity will point to a poor connection that will need to be cleaned.
 
stiligFox said:
If both relays are original then there is a good chance they?ve succumbed to solder cracking due to the bad heatwave soldering job that many Volvo relays recieved. I haven?t cracked open my original relays yet but I got two new KAE relays that are working just fine for now.
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Is this possible even if I feel them ?click??? In KP2 I could feel the RSR click even during a no start.

I am probably going to throw a crank sensor at this thing in the near future just for peace of mind.
 
PromiseRing said:
Is this possible even if I feel them ?click??? In KP2 I could feel the RSR click even during a no start.

I am probably going to throw a crank sensor at this thing in the near future just for peace of mind.
Click to expand...

I?m not sure - I know in the case of my headlight relay, it still clicked like normal even when it obviously failed. It could be the switch inside is working but voltage leaving the relay isn?t, or something like that.
 
Ok so if you suspect lack of current to the injectors I would just bust out the test light. Does it illuminate between injector positive and a good ground (key on). That would verify RSR relay operation.

Then use your test lamp to a B+ source like the alternator or battery positive, then poke the other end to the injector negative and crank. Test light blink=good ecu injector control.

Do you have a test lamp? They cost $5. Or build one from a spare bulb and some wiring.
 
No test light unfortunately. A test light and a noid light kit are on the to-buy list.

Just looked over the wiring diagram for the RSR. Black is a constant ground. Red is a constant 12v. Blue+yellow is a switched and fused 12v. Green+red is straight to each injector Orr??? Anything right to the LH box itself? Kinda confused on that. Going to check continuity on each of the 4 wires during the next no start.
 
You should stop and get/build a test light.

The last test lamp I bought cost $1. It's in the trunk of my daily.
 
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Today it started fine, got to op temp, then parked for 1hr-1hr30min. Then a crank no start. I bypassed the RSR by jumping the 12v RED wire to the RED + GREEN wire and it did nothing. So the relay itself is not at fault here, but rather the wiring?

Waited like 5 minutes and it started right up.
 
lummert said:
The fuel pump relay triggers the RSR. The fuel pump relay is grounded through the LH ecu.
Click to expand...

So ground should be good since I know for a fact that the fuel pump relay is good and turns on both pumps reliably as it should.

Today when we had a no start again I grabbed a jumper wire and ran it from + post to the red/green wire and the car started. It?s startinf to look more and more like a + wiring issue. Once clean new relays are installed along with new + wiring to the battery, we will see how it goes.
 
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