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Hello - looking for a little clarification after reading the threads. I'm trying to diagnose a hard cold start, lumpy acceleration issue on my 84 wagon. I thought I had narrowed it down to one of the system/fuel pump relays and replaced the supposed faulty one, but no change in behavior.
Should I be hearing both pumps when the key is in position II or only the in-tank pump? And does it continuously run, or when pressure has been built in the system does it stop running? The in-pump is only running (audibly) about 1 in 10 key cranks and only for a few seconds, which I understand to be correct.
I do not hear the main pump at all in position II, but believe it to be functioning as I can hear them both run when jumping the fuses.
Any insight is appreciated!
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84 245 manual, 365K
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If it were hard WARM start you were chasing, I'd chime in with N about the check valve. I've had several of those go bad with rusted springs back in the days before the fuel we buy had ethanol in it.
But hard cold start is "a thing" with the 84. Volvo added a little boost to the start enrichment with a TSB. Besides that the old -002 AMMs deteriorate toward the lean side with age. Someone will know the TSB number if you're skeptical -- I don't.
Here's the TSB, but from my own independently arrived conclusion. The starter signal boosts fuel via the ECT input on the ECU. Volvo did this under the hood, so look for a mod along the blue wire across the firewall from the ECT to the ECU.
I did it in the harness at the ECU plug.
And, no, LH2.0 doesn't buzz the pumps with key on. That's k-jet and LH2.4/3.1.
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Art Benstein near Baltimore
As told by G.Downs III:
After years of hiding the fact that the love is gone, the last child moved out of the house and Mom and Dad announced they are getting a divorce.
The kids are distraught and hired a marriage counselor as a last resort at keeping the parents together. The counselor works for hours, tries all of his methods, but the couple still won't even talk to each other.
Finally, the counselor goes over to a closet, brings out a beautiful upright Bass, and begins to play.
After a few moments, the couple starts talking.
They discover that they're not actually that far apart and decide to give their marriage another try.
The kids are amazed and ask the counselor how he managed to do it.
He replies, "I've never seen anyone who wouldn't talk during a bass solo."
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Hi Art,
I did not know about the modification per a Volvo Technical Service Bulletin or as far as that goes, Where you would even get copies of those to look up by a number for one?
You sure do know your stuff to be ahead of them!
I will have to check to find out if a dealer put that modification is in someplace.
You pointed out to me that the car must have had the wiring harness replacement done to last this long without issues.
I told you back when that I looked and It doesn’t look totally factory because it has a split loom used.
Maybe the dealer followed directions and it’s in there. The PO’s took their 850 religiously to the dealer until the A/C became a boondoggle to get fixed.
Cracks in the evaporator tubing was my diagnosis.
They kept charging it up trying to get it past the warranty. Finally a TSB got stirred up from someplace or somebody and receipts for other charges hit the proverbial fan.
My 84 has always fired up super fast since I got it. It’s faster than my other cars most of the time. Just a click when cold but a little slower the rest of the time.
That is why I knew it was in good tune as I did most of it about 15 years ago @105K. They were friends of my wife’s at her work place and she volunteered me to look it over.
I got it fixed up to a point but suggested the AMM might be going south.
Later they had it changed, by whom I do not know. A dealer maybe or just modified and charged for the AMM. The owners only told me the box under the hood got changed and it did run better.
All of this just before the car got hit in the rear door from a car rolling loose down a hill in a motel parking lot. Failure of a Sabb driver failing to set his parking brake while checking to rent a room. The insurance companies wanted to total the whole car, on the theory, it might have bent the frame.
I bought the car back through them for $700. I offered more but they wanted the car to go to a good home! They saw the car last year. They spotted me in it at a popular pizza place in town.
They drove up in their new white Toyota SUV with more comfortable seats, than their older Chrysler car, that they went to, after leaving that 850.
I didn’t say it, but they are in that seven year cycle!
Now the ‘84 is holding steady at 186k all summer.
Looking for the modification along the firewall will help kill some time down south this winter.
Thanks,
Phil
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Hi Phil,
I wouldn't say I beat Volvo to it. Far from that. But when I learned of the TSB and its approach was the same as mine, I felt a bit better about "cheating."
From about 10 years ago: https://www.brickboard.com/RWD/volvo/1201181/220/240/260/280/experience_setting_amm_led.html
That's interesting about getting the car with the door pushed in by an errant Saab. We got our wagon at a discount 17 years ago, for a similar reason, and it took me two years to find a door the same color. Because, after the door was replaced, I failed to swap the build label, Mrs. B got told very firmly by some authority, that our wagon was an 88, not an 89. It is an 89.
--
Art Benstein near Baltimore
And more from GD III:
I have several of each awaiting time and inclination, as the Tower of Pisa said to Big Ben, "If you've got the time, I've got the inclination."
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Left out the punch line:
And for that, the counselor gets $200/hr, and doesn't have to join the musicians' union....
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Do you mean more like this? It's work of Art! :)
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Hi,
I have a 84 sedan and had a hard start time with it once. I narrowed it down to the fuel pressure regulator leaking off its rest pressure over night or if it set long enough in shorter times.
The FPR regulates extra fuel pressure, on the rail, under acceleration, as it is vacuum controlled.
Under acceleration, throttle open, the vacuum drops, closing off the flow of fuel to the return line, that goes back to the fuel tank.
The 1984 FPR is different in the way it attaches to the fuel rail but I believe it functions in the same way as later models but might fail more often. It’s just a suspicion or wild guess! (-:)
This is the only car, of my five cars I presently have, that one has ever failed.
I have wondered if it could be updated with a newer fuel rail, altogether?
I have not read anywhere that it has been done, but I don’t surf around a lot!
Only on the 1989+ Years does the ECU temporarily run the pumps for a second or two to pre-pressurize the fuel lines for faster starts. This is where you are getting information about position two of the ignition switch.
After that, the pumps do not run until the engine cranks over.
A signal is sent from the distributor or a CPS before either years of cars will run.
The 1984 signal to the ICU that’s located in the engine compartment and then, the ICU signals the ECU in the cabin. It’s located on the right side of the passenger foot well.
The 1989+ cars has both computers located in that cabin area.
This car uses two square silver relays that are interchangeable.
You found those, I think.
One is for the pumps and the other one is for fuel injection. Both have to pull in ( or turn on) simultaneously for the car to run.
I have had one of these fail from a bad magnetic coil. I temporarily opened the can and manually closed it to get home with a shoe string. I now carry a spare in the car!
On those next later model cars ( ? 1985 + ) these were replaced by a relay with two contacts inside one box for consolidation.
It is “Not” for easier diagnosis purposes. These suffer solder connection issues depending on what country or suppliers used.
If one side fails to close you have to figure out which side and why. Carrying a spare that you know is good works as well!
A bad in-tank pump will present more problem in starting period if the tank goes below a half full situation. It’s unlikely that you will ever hear that pump run, unless you do jump the pumps separately and lay under the tank or listen from the filler tube.
Hope this helps give you some “clarification.” Haven’t seen you on here much before? You are a newbie. Welcome!
(:-) Nice term to use in water treatment plants, after all that rain Texas got!
Phil
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Excellent, thank you very much. No, not a newbie, exactly, but wasn't able to log on for several months and finally just started a new account, and now can't get to all my old, saved threads, etc.
I've replaced the FPR within the past few years, so did not suspect that. However, I've had the car for 16 years now, having done one thing or the other, and what seems like "yesterday" turns out to be 10 years ago! (like the in-tank pump replacement). Or, I get confused from what I did when I had my '93 for seven years.
I've since tried interchanging the two relays to see if there is any difference, but no change. I'm headed out to clean all the electrical connections in the path, as I've found more than once - and is well documented here - it can make a huge difference with very little clue as what was the culprit in the first place. I had a few weird high idle surges crop up in the last few days to add to the weirdness.
I appreciate the detailed response and will try to follow up if I can get some resolution.
Craig
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84 245 365K
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Hi, so you are as new as I thought.
You mention exchanging relays around. That will not prove anything except if a relay was truly dead.
Both relays have the capability to shut down the engine at any time.
The trouble is in the early stages of failing relay is they can go out intermittently.
The fine wire windings of a coil heats up during use and what can happen is a turn of wire breaks but is still held in place by the others. This wire can then separate internally several times or just once if your lucky. This heating also treats a solder joint the same way if the solder only cracks or corrosion sets in.
If the pumps do run when it cranks but the car does not start, the injection relay could be dead.
If you switch the pump relay over to the injection side and the pumps do not run, then the injection relay is dead.
The car will still not run, but Luckily, You know the injection relay was dead though.
In this case you know you are on the side of the road with a dead relay. I had this happen so I opened it up wrapped a shoe string or anything non conductive over the top of the contacts.
From this point on things are on all the time but the car will start and take you home.
Same thing can be done to the newer cars with the double relay. These cars do have the beauty of being circumvented like a ship Star Trek Enterprise. It also helps to have a little “Scottish wisdom” to fix things on the cheap.
The thing you said about “lumpy acceleration” and a “few weird high idle surges” in the last few days has me thinking deeper. The best way for that to happen is, it’s getting an extra gulp of air!
Throw in a hard start when cold means lean mixtures too.
A sticking open IAC or a crack in the snorkel tube from the AMM to the throttle is an option.
If this car gets a too lean a mixture and a misfire occurs “the system” is so fast that the IAC and the injectors will try to adjust the idle speed for the fault. It will bump up the idle either by fuel pluses and the IAC flipping its self one way or the other.
Also in the SYSTEM, after warmup is the O2 sensor input telling the ECU what happen “afterwards.”
There is a temporary argument the ECU that has to resolve between the Coolant temperature and the AMM. It likely you are experiencing weirdness from the conflict.
The ECU is doing it best but is limited to what is written in the program by us humans and what shape of the components it’s working with are.
This is why there have been changes in LH’s 1.0, 2.0, 2.4 and the very limited 3.1.
What condition are the spark wires and the rotor? Due you have any random misfires?
I suggest you take notes and think in terms of what order are things happening. Like when going through the three stages of start, to warming up, to hot operational status.
Phil
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Check valve on fuel pump. Had a bad one on My 740T wagon. Starts
right up after replacement.
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Thanks for all the helpful information.
After a thorough cleaning of all the electrical connections, the problem has mostly gone away. However, I will still occasionally get a hard cold start and for a day or so, it would crank without firing for several minutes. It has always started given enough time. Typically, it fires, but no start. I wait for 10-15 seconds and try again. Eventually, it will fire long enough to start. Rarely do I have a problem starting once it's warm.
Art - I'm happy(?) to learn that the hard start is a "feature" of the 84's. I've driven this car for 15 years and it's temperamental to say the least. I'll have to consider the mod you illustrate. By the way, I appreciate and have benefitted from your advice here for quite some time, as well as tips from cleanflametrap.com.
Phil - I had an account on here for 10+ years, but couldn't log in for some reason and had to create a new account. Yes, I had a '93 that had the single relay. Thanks for the distinction about the various systems. I was wondering about the IAC - I have pulled it off and cleaned it, but it could be time for a replacement. I'll take a close look at the intake snorkel tube as well.
On my last tune up I replaced the spark plug wires and was amazed at the difference it made - completely cleared up a lumpy idle issue. The rotor and cap were replaced then, also, so not more than 1 year old.
Nahtanha - I'll check my records, but I believe I replaced the check valve when I changed out the fuel filter a few years ago. Thanks for the idea.
Craig
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84 245 365K
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