Draft p80 Master Volvo No-Start flow chart..please add to..

[abscate]

Feel free to copy and paste these suggestions into the boilerplate at thread top. Don't worry about order etc, we can fix that at end.

ECU troubleshooting won't be covered. One wouldn't direct a new no-start poster to the ECZu until they had run out all of the other options.

[northernlights]

check for spark

check for fuel

check compression...

in that order

I agree with Russ. I've seen hundreds of these and misfires and no firing is what we see most often.
If you want to make it useful post the methods of testing attached to solutions. (ie Listen for pump hum when key is turned or have a friend listen while you turn key - if no hum check fuel relay located at x (add pic) or add jumper to check for hum). When posters can find evidence of failure they will follow the correct method to repair/replace the part.

This is especially true for those who do not keep there car at Stage 0 as those who do are updating ignition components, oxygen sensors etc before failure or poor performance and get to avoid bad cat converters, internal piston and valve deposits, poor fuel economy etc.

Its always helpful to ask before doing anything.
Did you read the codes?
Are you at Stage 0? (explained as needed)

Spark, fuel and compression checks are best if you have points and a carburetor! Or an HEI, because the modules would reliably kill themselves every once in a while...

The problem with no spark is there are so many things that can cause it. Because unlike, say some old Ford's which will run without a working cam sensor, Volvo didn't like to guess, and will not let the car start without a functioning cam sensor. It accomplishes this by not firing the plugs, i.e. no spark, without anything being wrong with the plugs, wires, distributor, etc.

I think the best approach is a list of things to do when the car cranks but doesn't start, because that seems to be where most people run into trouble. Feel free to flame my suggestions!

Before any troubleshooting starts, it is well worth checking the all battery and ground connections, e.g. battery cables, firewall ground, etc. Bad connections can stop the car from running. The voltage across the battery terminals should be about the same (maybe a couple tenths more) as battery + to ground points. If you have old wiring and measure voltage from the taillight sockets to ground, then you are laughing at the thought of only loosing a couple tenths of a volt. Under the hood everything is closer and the wiring runs are shorter, so there shouldn't be a big voltage drop unless there is a problem. Loosing a volt under the hood is a lot.

If the car was running fine, and mysteriously died or will not start...

Assuming no wiring issues, I would start with fuel, because it is the easiest. Gas really wants to burn. The ECU has no way of initially knowing if fuel is flowing, so it will try to fire the plugs even with no fuel. So, if you introduce something combustible into the cylinders on an engine with a fuel problem, the car might start for a moment, or misfire, backfire, or make some other horrible noise.

In my mind, the best place to start is...
1) Fuel pump relay
These things seem to get possessed with age. I had one become intermittent on a 240, and I finally figured it out by driving the car until it died on the road. On the side of the road, I swapped in a new one that I carried with me while waiting for it to die. The problem went away, and 5 years later never returned. My 850 would want to stumble occasionally, but because I didn't feel like troubleshooting and the relay was old, I replaced it just in case, and keep the old one in the glove box. As before, the problem seemed to go away.
Remove and bypass with a jumper.
If the car starts like magic, it's bad.
If the car doesn't start something else is bad....and the fuel pump relay might also be bad! (this sucks)

Leave the jumper on for the rest of the troubleshooting, making sure you remember to remove it before you are done. This eliminates a bad fuel pump relay from the equation.

1a) If you have the tool, check the fuel pump pressure at the rail when you turn the key on. With the relay jumpered it should spool up and give you a number. I believe the spec is 3 bar when running on all of these, but I don't know what the number is for key on. If it doesn't at least twitch, then you probably have a fuel delivery problem.

2) If you don't have the tool, or if it looks like the pump might be bad, shoot some ether (starting fluid) into the intake. There are a bunch of vacuum fittings after the throttle that will work as an access port without having to take the air hose off. If you don't have ether, a little gas works! Anyone who had a car with a carb knew you had to pump the gas a couple times (at least) before a cold start, and all that did was shoot liquid fuel into the intake manifold. The amount of liquid fuel floating around a carb'd engine was amazing, and that's why they wore out so much faster than injected engines. The old holley accelerator pumps were good for a cc or two per pump (the big ones were 50 cc max per 10 pumps), so a little goes a long way. Too much will flood it, but remember, gas wants to burn.

If the car now pops, misfires and/or hiccups, then you have a fuel delivery problem. I say this because, for example, if the coolant temp sensor is bad, and it gets very cold, the car suddenly might not start because of insufficient cold enrichment. If that seems likely (as in, the car doesn't like December) then check the resistance of the sensor, because it's easy! Resistance spec is 7300 ohms at 32 F, 2800 ohms at 68 F, 1200 ohms at 104 F, and down to 150 ohms at 212 F.

If the car actually starts for a second or two and dies, you definitely have a fuel delivery problem. Unless you have a tank of bad gas and/or a very, very, very old and abused fuel filter, then your fuel pump might be dead. If it's December, I'd check the coolant sensor anyway just in case you get lucky.

If it doesn't look like a fuel problem, and the car was running well and dies mysteriously, then you probably have a component failure. I would first look at:

3) Crank and cam sensors

The crank and cam sensors will prevent the car from starting when they die. I believe the car will run with a dead cam sensor, but will not start, so if it dies on the road a crank sensor is more likely.

On P80's, the crank sensor has a resistance spec of 300 +/- 40 ohms. I measured my 18 year/150k mile VDO one at 317.5 ohms, and replaced it (because it was old) with a new VDO one that I measured at 292.4 ohms. I've seen aftermarket specs of 300 +/- 75 ohms. This is why I do not trust aftermarket because who knows how important the spec is.

They also have an inductance spec (70 +/- 10 mH at 10 kHz), but who knows how to test this. This is another reason to not trust aftermarket, because who knows what they are designing to if you can't test it.

If you have access to a crank sensor that came out of a running car, then it's probably worth swapping it as a test. There was a service bulletin in 1993 about interference from the ignition system, so these things are somewhat sensitive. If it looks suspicious, and you don't have a fuel problem, then I'd replace it.

The same goes for the cam sensor. I do not know a good way of testing a cam sensor, but I have noticed that the plugs seem to disintegrate over time, which can't be good from a signal standpoint. If it looks funny, replace it, or swap in a known good one if you can.

If the car was running poorly, and finally decided it didn't want to start, this is when I would start to look at the tune-up type things. This can be tough to tell sometimes, because many people have no idea when a car is not running right, and will drive it until it stops running, and wonder what is wrong.

4) Check the ignition components, plugs, wires, cap and rotor if you don't know how old they are. If the car was running right and then suddenly wouldn't start then don't expect this to be the problem. If you have previously replaced them with quality parts in recent memory then this probably isn't a problem.

The rotor actually has a resistance spec of 1.1 - 1.3 k ohms. This is easy to check. I would stick with OEM style (like Bosch) because if it has a spec, it's probably important.

The plug wires also have specs based on cable. Coil cable is 2 2.5 k ohms. The rest from 1 to 5 are 4.5, 4.0, 3.3, 2.9 and 2.3 +/- 20% k ohms respectively.

The coil has specs of 0.5 to 1.5 ohms between terminals 1 and 15, and 8 - 9 k ohms between the coil wire tower and either terminal.

After this, it starts to get complicated. Things like bad O2 sensors and MAF's will make the car run like crap, but probably won't leave you stranded.

[erikv11]

Volvo published a flow chart for this back in 95:

Volvo - Basic Troubleshooting.pdf

(94.21 KiB) Downloaded 937 times

[TBrown00]

I had a crank but no start issue about a year ago and it ended up being the fuel system relay near the fuel rail.

[northernlights]

Here's a couple of pages from the Motronic 4.3 book that I think are very helpful when it comes to troubleshooting no starts.

Note that a dead RPM (crank) sensor means no ignition or fuel, which means:

Engine will shut off,
Engine will not start, and
It might look like a fuel or ignition problem

A dead cam sensor will do the same thing, except it will not shut the car off while running.

Note that both will actually set codes under certain conditions.

Pretty interesting...

[This may or may not be the best place for this - is this worth a new topic?]

[abscate]

I think it can have both its own topic and also be added here..thanks.

I'll do some work on this later today

[JimBee]

Is the test for these parts simple continuity or do they have specific resistance values?

[rhd]

This flow chart is a terrific idea.
I just bought a '98 V70XC with a diagnosis of a bad fuel pump. I just replaced it with a new one, and it still won't start, but the pump is working. The posts on this page give a great start to troubleshooting it.
I'm a "shade tree" DIY person, learning by doing (often the hard way, giving Murphy plenty of opportunities to play havoc with me).
This site is great, and the contributors are very helpful. I'll post what the problem was once I get it figured out.

[misterclean12]

Coolant temp sensor caused me major headaches on my first xc70. Took me a month of throwing parts at it... Was mainly on hot re-starts but happened on cold starts as well as it got progressively worse. Would just crank and crank. Ambient temps were around 70-85 degrees. ME7 2.4t.

[pkc303]

You may want to add connectors to the relays. My connectors fell apart, and required repair. I had a no start issue; lack of fuel from the injectors due to the poor connection to the relay.