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1991 945 cold starting problem 900 1991

I have a 1991 945 with a B200F non turbo red block. LH 2.4 injection.
Owned since 1995 with little needing replaced.
But now will fire from cold, run for a very short time then stop. It cranks over vigorously after stopping but will not fire.
Left overnight and I get a repeat performance - starts easily then stops and will not restart.
There are no codes stored on the OBD1.
I have substituted the "radio suppression relay" but this made no difference.
Some guidance on what to try next would be appreciated please!

Many thanks
Ian F
Scotland








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    Hi Ian,

    I'd start with seeing if "Fuel, electrical" is behaving.
    (Dunno if there can be a faulty fuel line or fuel filter do this?)
    You can use your DC voltmeter on Fuse 1 and Fuse 11 to see if the DC supply is
    dropping to the fuel pumps when the engine quits.
    Use the cigar lighter ground and probe either ATC fuse leg up top.

    If the DC supply drops out then the fuel relay has a strong chance of being the culprit. It's easier to swap than to measure the relay in place. If your fuel relay is original I'd replace it with new.

    Be aware that swapping relays can damage the socket pins. When rocking and tugging relays out of the socket you can spread open the pins and loosen the
    contacts. You can make a gauge with the same thickness male spade lug
    crimped and soldered onto a stiff 12 or 14 gauge wire to check the socket pins
    before re-inserting the new relay.
    Loose socket pins may be the cause of toasted relay sockets.
    They can be removed and be tightened or replaced.

    If DC voltage doesn't drop out, you can check each fuel pump by measuring
    current flow at Fuse 1 (Both pumps) and Fuse 11 (in-tank primer pump)


    Here's one way to measure fuel pump current flow with your VOM:
    Compute current flow in ATC fused circuit by voltage drop.

    Use this chart to calculate the current from the millivolts readings probed at the top legs of the ATC fuses in place.

    https://m.roadkillcustoms.com/wp-content/technical-pdf/Standard%20ATC%20Fuse%20Voltage%20Drop%20Chart.pdf

    Most VOMs measure up to 10 DC amps tops. To measure higher current
    You can get an analog 1-50 DC ammeter with shunt at ebay and make a nice probe
    out of a dead ATC fuse. see here:
    https://www.brickboard.com/RWD/volvo/1687323/make_atc_fuse_socket_plug_dead.html

    OR (This handy option has time limitations)
    https://www.harborfreight.com/30-amp-automotive-fuse-circuit-tester-67724.html
    "30 Amp Automotive Fuse Circuit Tester - Harbor Freight Tools
    Product Overview This handy automotive fuse circuit tester has specially designed test leads that plug directly into your fuse box to quickly diagnose electrical problems. The tester can be used on all circuits up to 30 amps. Test automotive circuits at the fuse box, plugging into ATC blade-style fuse slots Simplify electrical diagnosis." Can you find HF in Scotland?

    The ECU controls the fuel relay: It needs good inputs to work right.
    Quality connections for signals and grounds are crucial.
    You can look here for a lengthy look at troubleshooting LH 2.4 engine management
    with many interesting items, including a specially modified fuel relay.

    https://www.volvoclub.org.uk/faq/EngineFIComputer.html

    Good luck, Bill



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      Some progress and a further question please.
      I have noticed that if I start the 945 and keep it running until warmed up, I have no problems restarting.
      What causes a non-start is if I start, switch off and try restarting, after a few cycles of this it refuses to start.
      With a voltmeter connected I find that the non-start is always when battery voltage falls below 12 volts (the battery and alternator are past their optimum).
      The engine turns over well at least than 12 volts, but no-start.

      My question is - does a low voltage prevent some relay or solenoid from operating, hence preventing a start!

      Ian F



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        Hi,

        I think you may be on to something with the battery voltage dropping after a few start up in succession.
        A warmed up battery, say from engine heats and alternator excitation will react differently for a short time.

        A battery in good charge, that is with its plates of each the cell having decent capacities, the whole battery should return up to very nearly to what was its resting charge within about thirty seconds.
        Most anything above 12.5+ volts is considered a working battery.
        12.4 volts, at rest for say overnight, means the battery is only half charged or less.

        On todays sealed batteries a load test is the only way to lock down on the battery’s condition short of measuring the electrolytes density.
        A low density means the solution has gotten into the plates and charging drives it back out.
        Eventually the plates become too resistant to continue working.
        It is beginning of saying that the cells are getting depleted of life expectancy.

        If the battery goes down quickly and after being put onto a charger to charge, it comes back up very quickly to chargers voltage the cell or one cell in particular maybe a problem.
        In actuality, the cells as a whole set do not ever get fully charged as current flow stops entirely if one cell blocks the chain.
        If a carbon cell, alkaline or rechargeable flashlight goes dead and it has more than one battery cell …… please check the others in the light. You might find that the others are still capable of being used longer.

        Car batteries are being used the same way but you cannot separate the good ones from a bad one.
        Even still with this knowledge if one cell is troublesome they all will be soon.
        The aging part is significant to all.
        It’s the nature of lead acid or chemical cell batteries.

        Follow those instinctive signs you are seeing, I would or have before!


        Electric cars will be faced with the same issues if they continue to promote batteries as a power source.

        Haven’t we learned anything since the late 1800’s?

        There’s been Nuclear since the mid 1900’s and it is not a consumer friendly rated concept at all!

        Photo cells and Fuel cells that have gone into space and with no mechanics or service calls.
        Their NASA lives lasted longer than we ever expected too.
        Apparently we have capabilities.

        Hydrogen has spread out throughout the universe as with carbon in many forms.
        So I ask, for an explanation of why are we still manipulating “hazardous waste chemicals” like lithium or uranium.
        Haven’t we learned anything?
        Yes, I have a clue, don’t you?

        Phil



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          do you have a air leak at the point where the header meets the cat? It could be leaking extra airin& clogging the cat w uv carbon eextra fuel??



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          do you have a air leak at the point where the header meets the cat? It could be leaking extra airin& clogging the cat w uv carbon eextra fuel??



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          I think I have solved this one. Probably operator error rather than a fault with the 945.
          It seems that this sort of problem has arisen before in 940's of this vintage, found out through the UK Volvo forum.
          The issue seems to be the 5th injector - the cold start injector. I believe this was deleted by Volvo shortly after 1991 as it was causing problems. Multiple starts on a cold engine cause fuel flooding. The solution is to hold the throttle fully open and churn the starter. The engine will then start with a rush once the excess fuel is dispersed.
          This works for me.
          The lesson is - don't do multiple starts on a cold engine if it has the 5th injector.

          Ian F



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            Volvo issued a TSB way back when that was meant to solve the cold start flooding problem. It involves snipping one of the wires connected to the CSI. Go here for more details:

            https://www.brickboard.com/FAQ/700-900/EnginePerformanceSymptoms.htm#ReginaColdStartTSB



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            Owen,
            I believe that it is actually a good solution on most if not all flooded fuel injected engines. I had a similar problem on my 95 850 sometime ago. Couldn’t seem to start it no matter what I tried. Read about something called lawn mower syndrome on the AWD forum here on the BB. Like you, I kept the accelerator floored and cranked the starter and happily it fired after weeks of not starting…:)
            Jim
            --
            Will I buy another Volvo??? We'll see....



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        Hi Ian

        Where did you connect the voltmeter?
        Don't worry about system voltage readings while the starter is spinning.
        Measure the battery at the battery, and get 12.6 Volts engine off
        and 14.0 Volts engine running.

        Is there voltage at Fuse 1 and 11 when it fails to start?
        Measure Fuse 1 and 11 as discussed.
        How much current draw for each pump?
        Read DC millivolts at the top legs of the ATC fuses and use the voltage drop
        chart to get DC Current values.

        Bill



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          Thanks Bill. The voltage is at the battery. The voltage drops below 12 after 2 or 3 starts from cold, and this is when the engine turns over but will not fire, hence my question whether this lower voltage could be preventing some component from operating.
          At the moment I am still trying to determine exactly what conditions prevent starting before doing anything more complicated. I have to admit some of the options you suggest are probably beyond my competence!
          After an initial start, voltage over 12.5, it runs fine and if left to warm up (and charge the battery I guess) it will restart without any issues. So it seems to me that there may be nothing fundamentally faulty with the vehicle.

          Ian F



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            How old is your battery? Did it ever freeze when discharged?

            Take the battery cables off and clean the battery cable clamps and battery anodes
            with a battery (wire brush) tool. Grease and reinstall.

            Measure the voltage afterwards engine on and off.



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      Thanks Bill, that's great - a lot to chew over!!
      No, we don't have Harbour Freight in Scotland or the UK as far as I know.

      Thanks again

      Ian F



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    I would start by determining if you have a fuel or electrical problem. When it won't start give it a healthy shot of starting fluid and see if you can get a short run out it.

    If it is an electrical fault I would start by removing the coil from the module it is mounted to and clean up the contacts between the two. That is a long shot but over time they have a tendency to corrode somewhat.

    Is the car running long enough to get up to operating temperature?
    --
    Any twenty minute job is just a broken bolt away from a three day ordeal



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      Thanks both. I will have a look over things today and may be back with more questions!

      Ian F



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    Dear Owen,

    Hope you're well and stay so. This problem likely is electrical and has to do with the fuel supply or spark. An item, at the end of its service life, heats-up. That breaks a connection. Until the item cools - restoring the circuit - the engine won't start.

    Over time, soldered joints can develop micro-cracks. Years of heating and cooling - and expansion and contraction of the solder - break the connection. These micro-cracks are far too small to be seen with an unaided eye, but suffice to disrupt a circuit.

    When were the following replaced: (a) fuel pump relay; (b) crank position sensor; (c) ignition amplifier?

    Hope this helps.

    Yours faithfully,

    Spook



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