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Old 12-08-2019, 03:27 PM   #1
Mbeas96
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Default Classic failed ECT?

Solved. Page 4 post 80.

90 745 lh2.4, I'm not near the car but have been having issues as of Monday morning. I'm just posting to see if anyone has other ideas I could dig into when I get time.

Monday 6am; it's 33° outside and the car won't start. It cranks fine, battery seems strong, and it wants to fire but will not stay running. Might have one or two chugs but that's it. Took 10 minutes till it fired and when it did start seemed like nothing is wrong.

Same story for Tuesday morning before work, and literally everyday after except for Friday. I didn't have work and didn't go to start the car tI'll 11am ish and it was 55-60°, started fine with no issue.

No CEL and no codes stored, and it *seems* to only happen on a long sit overnight and it's below 40 degrees or so. The car can sit for 10 hours while I'm at work, be 45 degrees at 5pm and it'll start no problem..so this is why I'm questioning my theory of ECT failure.

Any suggestions?

I did notice my fuel pump relay might of been flaky, didn't hear the pump turn on every time I urned the key to ON , swapped with a new one and I now hear the pump prime every time but still no start
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Old 12-08-2019, 05:42 PM   #2
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Similar symptoms when FPR is by-passing.
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Old 12-08-2019, 08:46 PM   #3
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I doubt it is either one. You may have a fuel pump check valve that doesn’t work anymore. It’s hard to get the car to start when they are not holding fuel pressure.
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Old 12-09-2019, 07:55 AM   #4
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Ahha now running and driving issues ensue...got back late last night and had to drive to work this morning. Hard cold start like usual, but then choppy idle, really like there is a big cam. I can smell gas when idling and slow driving, it has no power and when trying to accelerate it misses more so than not. Wide band shows it dive into the 12s when the obvious miss happens.

Made it 30 miles to work and car restarted without issue when I arrived. I have several used parts on hand including a fuel pressure regulator, a set of plug wires and an AMM. Lunch should be fun.
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Old 12-09-2019, 10:06 AM   #5
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...fuel pump check valve...
On LH 2.4, I prime the rail, so that I engage the starter before pump is turned off. I've done this priming for years on Berettas, and now Volvos (LH2.4 & Rex-I/Reginna).

When I bought a 1990-240 this year, its fuel pressure regulator was by-passing, and main pump was revving and not slowing down, which I could hear, and hard-start existed. It would run fine, once started.
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Old 12-09-2019, 10:51 AM   #6
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I have heard over the years you should always prime the pump before trying to start. I did try and prime it 5 times before starting on Tuesday morning and it seemed to help. But then again before trying that I was cranking on and off for 10 minutes.

The pump primes and then stops as it should.
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Old 12-09-2019, 03:45 PM   #7
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The pump primes....
Pump runs for a short time duration, then ECM shuts it down.

Point Made - If pump RPM is not slowing down, then FPR may be the issue.

Thus - Do an ECM prime....turn key off...do another ECM prime...if pump's RPM does not slow down, then fuel is by-passing, and rail pressure will be lower.

Needless to Say - Never run on a near empty tank, especially when in-tank pump is not working, and during hotter weather. In-tank pump didn't come with 1975 240s, and there was vapor lock issue. I kept my tank on full side, just in case in-tank pump fails.
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Old 12-09-2019, 04:01 PM   #8
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Quote:
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On LH 2.4, I prime the rail, so that I engage the starter before pump is turned off. I've done this priming for years on Berettas, and now Volvos (LH2.4 & Rex-I/Reginna).

When I bought a 1990-240 this year, its fuel pressure regulator was by-passing, and main pump was revving and not slowing down, which I could hear, and hard-start existed. It would run fine, once started.
It can't possibly run fine if the fuel pressure regulator is bypassing the fuel. That is a key component of the fuel system. No fuel would go through the injectors. Or, so little the car would start and idle, yet, wouldn't be able to pull itself across a level parking lot. On a k-jet car, it won't even start if the regulator isn't holding adequate pressure to open the injectors.
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Old 12-09-2019, 08:36 PM   #9
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It can't possibly run fine if the fuel pressure regulator is bypassing the fuel.
Huh? I know if you choke-off return line, rail pressure can climb to around 100psi.

ECM via O2 will increase pulse duration...same when slightly "over-sized" injectors are installed, ECM will adjust to shorter pulse duration when O2 reports richness.

Run Fine - In regards to a typical driver's pedal input.

ByPassing - Partial bypass...not complete bypassing.

PS: Been here, done that (replaced a FPR doing a partial by-pass).
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Old 12-09-2019, 09:49 PM   #10
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Right. They are always bypassing a certain amount of fuel in order to hold a constant pressure. Your post indicated to me that you are saying it is completely bypassing the fuel and not making any pressure. If that were the case the car won’t even start.
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Old 12-10-2019, 06:00 PM   #11
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No data yet, but it ran fine yesterday on the way home in about 60 degree weather. Started and Drove completely fine this morning in an unusually hot 65 degree morning.

When I say driving fine I mean there is no gutless feeling, afrs are spot on during WOT and everything feels like it has for the last 2 years. I'm wondering if I could of just restarted and the problems while driving would've dissappeared.

Also, I've had less thank half a tank for the last 2 weeks...it doesn't seem to affect it.

I'll check fuel pressure soon, and the check valve...by the inline pump? Is cleaning an option or a replacement is probably needed?

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Old 12-10-2019, 06:02 PM   #12
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The check valve is screwed into the front of the fuel pump. They are replaceable if you can find one. Cleaning it won't help.
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Old 12-10-2019, 06:28 PM   #13
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Volvo Fuel Pump Check Valve - Bosch 1587010539
240, 242, 244, 245, 740, 745, 760, 780, 940, 960
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Old 12-14-2019, 10:37 AM   #14
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Leaving work yesterday, for the first time it happened not in the morning. Took a couples cranks to finally fire, drove away, within 300 ft car shuts off. Cranked a couple more times to start again. Slowly turn back around to the parking lot and car shuts off again. Scared I'm gonna need a tow home, I started it and let it warm up sitting there. Drove home with a strong gas smell and by the gauge reading, I'm losing gas way faster than I should. (About a quarter tank for 30 miles)

This morning I finally have some time to mess with things. Checked fuel pressure. 42psi on the first key turn and it holds, when cranking it drops to 40psi. Haven't checked it running because I haven't started it yet.

Even though that reading seemed fine, I swapped FPR's to another I had laying around. No change.

Swapped spark plug wires because they are easy and no chage.

What's next? Unplug injectors and starting fluid?
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Old 12-14-2019, 11:21 AM   #15
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Pulled the plugs and other than them being a little wet with gas from the few times I tried to start, they look pretty good.

Had a hard time getting a good picture with all of them, so one at a time...

Resized_20191214_095640.jpg
Cylinder 1 (front of engine)

Resized_20191214_095654.jpg
2

Resized_20191214_095703.jpg
3

Resized_20191214_095713.jpg
4 (back of engine)

I then checked for spark by putting a plug in each wire off the coil and laying it on the strut tower to ground, while my girlfriend cranks.

I saw a very weak spark from all of them. I BARELY could see it. Granted it's not dark outside, but I feel like they should be strong pulses rather than very light very weak looking spark.

I tried to take a video, but it's so weak it doesn't show up on my camera...tried multiple plugs in each and same result.

Before going to get starting fluid, would anybody think spark is my issue, rather than fuel?

Ehh, here's the video for kicks and giggles

https://youtu.be/JR_vvtQNEvg

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Old 12-14-2019, 11:54 AM   #16
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But then there's threads like these that just make me wanna spend the next few hours changing the ECT (minus the code)

http://forums.turbobricks.com/showthread.php?t=210
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Old 12-14-2019, 12:48 PM   #17
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Finally got the car to start after 30+ crank attempts. Let it warm up and restarted first key turn. The wide band shows it idling around 14.7, but with a warm car there is smoke coming out the exhaust with a strong gas smell.

checked fuel pressure while running, again 42 psi on prime, drops to 40 while cranking, then idling it's around 37-38, but then with throttle it drops down to 33-34 and as soon as I let off the throttle it shoots down to 30 before rising back to 37-38.

That seems like a problem, yes? Maybe one of my pumps is failing?
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Old 12-14-2019, 02:00 PM   #18
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Quote:
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I'm losing gas way faster than I should.....let off the throttle it shoots down to 30
Cold start injector pissing away? Loose rail pressure when key is switched off?

Ohm spec coil, and check related grounds...swap out ignition module

>wide band shows...14.7...smoke coming out the exhaust

Perhaps excess fuel remnants "burning off."
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Old 12-14-2019, 02:07 PM   #19
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Quote:
Originally Posted by Mbeas96 View Post
Finally got the car to start after 30+ crank attempts. Let it warm up and restarted first key turn. The wide band shows it idling around 14.7, but with a warm car there is smoke coming out the exhaust with a strong gas smell.

checked fuel pressure while running, again 42 psi on prime, drops to 40 while cranking, then idling it's around 37-38, but then with throttle it drops down to 33-34 and as soon as I let off the throttle it shoots down to 30 before rising back to 37-38.

That seems like a problem, yes? Maybe one of my pumps is failing?
The regulator is working like it should. Higher vacuum = lower fuel pressure. Snap the throttle shut and you have high vacuum. 42-45 psi with no vacuum is right where it should be.
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Old 12-14-2019, 02:45 PM   #20
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Should of started with the car details, but I was going towards a classic ect failure...

1990 745 lh2.4
Wasted spark conversion using miata j702t ignition module and 2x2 coil pack.
Fuel rail swapped for one with a schrader valve and no CSI
Cold start injector is deleted and manifolds are swapped
954 chipped fuel ecu as my original 563 had some other issues

I have a spare coil pack I will swap in and possibly another ignition module as well.

Since it's warmer now, I doubt the starting symptoms will be there. I'd rather try starting fluid first before pulling the rail for a fuel injector test, but I'll end up having to wait till tomorrow morning.

It's apparent there is a fuel problem. But if its to much or not enough spark to ignite it, I'm still unsure.

I'll recheck to see if pressure drops after car is turned off
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Old 12-14-2019, 05:12 PM   #21
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I'd replace plugs...off-hand, it appears they have soaked up some oil, via intake valves or rings, or maybe fuel. Plugs firing via wasted spark should appear cleaner. Soaked plugs loose their full potential.

If fuel rail pressure drops, when key is switched off, this test is valid for detecting a leakie injector only if FPR and Fuel Pump Check Valve (Bosch 1587010539) are holding.
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Old 12-14-2019, 05:53 PM   #22
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Gotcha, I'll pick up some fresh plugs today, ordered a bosch check valve, it'll be here hopefully Wednesday.

Rechecked fuel pressure when car turns off, in the first 30 seconds it drops from 38ish to around 23psi. Then it held for a a minute or so until I took the gauge off.

Is it supposed to hold pressure longer? Or does this seem okay?

I also cleaned the ground for the ignition module I have ran to one of the strut brace bolts. We won't know until tomorrow morning if that's the culprit or not. It did look kind of crusty and brittle.
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Old 12-14-2019, 09:31 PM   #23
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...drops from 38ish to around 23psi....
When K-Jetronic hits rest pressure of 24 psi...it had to maintain this pressure for one minute...then after twenty minutes, rest pressure should not be lower than 14 psi.

>first 30 seconds

Via testing GM vehicles, yours is dropping like a rock, so either FPR or check value issue, or leaking injector(s).

>supposed to hold pressure

The more, the better...otherwise more cranks on engine, unless pumps are activated first.

Pre LH2.4 vehicles had to crank engine before pumps would engage. LH2.4 allowed pump priming via turning key to on position. Hence, pre 1989 Volvos had to maintain fuel rail pressure....if not enough pressure, crank, crank, and crank.
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Old 12-14-2019, 10:57 PM   #24
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Well, the check valve will soon be replaced. Even if it's not an issue, new is better than the unknown.

I'll recheck some things tomorrow morning, probably pull the rail and check out the injectors unfortunately.
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Old 12-14-2019, 11:18 PM   #25
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You keep questioning the ECT, just change it already. https://www.fcpeuro.com/products/vol...sensor-1346030 Drain a little coolant from the block drain on the exhaust side, 3/8 ratchet with long extension and 3/4 socket. 20min and done, not sure why you are thinking hours. I was having rough cold start, idle hunting, etc; changing this sensor resolved the issue.
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