First, I'll say that I know technically my post might belong more in the other classic forum, but mechanically my 780 Bertone has the B230FT that you're all familiar with.

So then, on to the issue. I bought my 780 Bertone from an estate sale with 88,755 on it knowing it was inoperable at the time. The previous owner said that it belonged to his deceased father and had been in storage for some years before he tried to get it running after his mother passed away. He told me he drained the fuel tank and installed a new fuel pump and filter and it had run fine before sitting some years after that. When he tried to get it to start at that point, he was having trouble getting it started. With the help of ether in the throttle body, he claimed it ran but that's as far as he got, so it was presumed to be a possible FI system relay problem or fuel delivery. That takes us to the past week of me tinkering with it.

I've ruled out the following culprits:

1.) Starter works fine, has a fresh battery-H6 group size.
2.) Fuse 1 and Fuse 11 are intact, the vehicle has 2/3 tank of gas which is somewhat yellow but doesn't appear to have water.
3.) The FI relay was replaced with a brand new Volvo OEM Stribel unit.
4.) The camshaft rotates upon starting.
5.) The ignition coil produces a blue spark upon starting.
6.) The tachometer "flutters" when starting, which should rule out the Hall sensor.
7.) After disconnecting the fuel supply line from the fuel rail, I verified healthy flow of fuel from the main pump upon cranking.
8.) With the key set to "run" all four fuel injectors show 12.3 volts.
9.) The ballast resistor appears to check out, but I may not have diagnosed that properly. Same goes for the ignition control module (unit on driver/left hand side inner fender).
10.) Aside from being somewhat fouled, the spark plugs seemed to be in decent shape and were the correct NGKs. Cleaning and replacing them made no difference.

Things that may still be suspect:

1.) Is the auxiliary suppression relay indeed beside the air intake box? I haven't checked that yet, not sure if it's the problem.
2.) I still need to borrow my friend's noid light to ensure the fuel injectors are operating, despite getting 12.3 volts.
3.) Said friend also has a spark tester I can try, so I can rule out anything associated with the distributor.
4.) I haven't checked compression yet, same friend has a tester.
5.) Something I probably missed?

I know it's kind of a long post, but I figured it's best to be thorough. I'm still not entirely sure how to check some of the components properly, like the ballast resistor, ignition control module, and auxiliary suppression relay. Have multimeter, will travel. This is a really gorgeous car and it's a shame that it's so close yet so far. Any help would be fantastic. If we can possibly figure this out, maybe I can post some "after" pictures!

 

Note the 780T has more in common with the 760 Turbo than the 740, in particular the electrical systems are completely different behind the dash, with different fuse panels, relays, etc.

if you're getting spark, you've eliminated any issues with the hall sensor, ignition power module, etc.

if the suppression relay was dead, you wouldn't see 12V on the injector side thats connected to the ballast resistors. you might see voltage on the injector side thats connected to the ECU when the injectors are unplugged. I believe that suppression relay is on the left fender, fairly forward and near the ballast resistors, which are connected to the relay's output... at least, thats where it was on my 1992 740 T. I had a 1989 780 new, but it was a V6, and I only owned it for 6 months and 20K miles, it was destroyed in a crash. *lovely* car to drive and ride in..

at this point, yeah, noid light test is probably next up. a fuel pressure test would be good, too.

 

In this case, a car unknown to you, you should start with a compression test to eliminate the basics that may affect the motor' condition.
The gas in the car now could also be a factor if older than 6-12 or more months, you really don't know about it. One shouldn't rely on sellers' representations, ever!
I'd squirt some ether in the intake to see if it fires up, easy to do, and a sure test about fuel being the problem.

 

Thanks for the suggestions, pierce and lev.

Just finished the noid light test. Passed with flying colors.
I'm waiting for a friend to come by so I can observe the spark test while they crank. If I get nothing from that, I'll probably test compression.

Is it possible that the old gas may have fouled or varnished the injectors to the point of plugging them? Also, I checked the FPR, and there were no leaks past the diaphragm that I could detect. Will keep you all posted.

 

therre's actually a connector under the hood you can use with a jumper to run the starter... I think its a pink or a blue single spade lug connector, but Im not sure where it is on your car. IIRC, the wire to this connector is pink. the remote starter is a handheld pushbutton, with a spade lug that plugs into this connector, and a clip lead to the battery + terminal.

 

Spark seemed fine. Compression was a little low on cylinder 1, but was much better after a little ATF soak overnight. I drained all the gas, filled it with 5 gallons of fresh non-ethanol 87 octane, charged the battery up, and installed new spark plugs just for the heck of it (the old ones were still a little wet from trying to start it with fresh gas).

No dice. The pump pumps, it has adequate compression, electricals check out, no more suspect gas - I ran the gamut. Time to let it go to someone willing to go over it with a fine tooth comb. I just don't have the time and patience to inspect every inch of wire when there's no explanation for the no start.

 

fyi, the turbos prefer premium gas, but that won't cause a non-start, low octane will just trigger some pinging at high throttle high load conditions, like full throttle up a grade in 3rd gear. they have knock sensors, so if they start to knock, they retard the ignition and the knocking goes away at the expense of power.

i think i'd crank it over some, then pull a spark plug and see if its damp with gas. if its dry, then you're not getting any fuel, which might mean clogged injectors, or inadequate fuel pressure

 

Thanks for the response, pierce. I'll probably pull the rail and check the spray pattern next.

 

Squirt some starting fluid in the intake, you will know immediately if it is a fuel problem.

 

Good idea, I'll do that. Do you just separate the main hose from the intercooler and spray there or directly into the throttle body?

 

The car ignited, then died, after spraying starting fluid into the intake tube off the intercooler. I was able to do this several times. I guess pulling the rail and checking the spray pattern is next?

 

So, now you know it's a fuel issue. Check fuel delivery, pressure...

 

This will probably sound stupid, but if I got a flow of about 1 GPM draining the fuel tank via the high pressure fuel pump, that should rule out that, right? So I'm guessing the problem is at the rail.

 

yeah, i'd do a fuel pressure check, which requires a T-adapter you put in between the fuel line and the fuel rail, where the T goes to the fuel pressure gauge. with the pumps running and the vacuum line disconnected, the fuel pressure should be 42-45 PSI (from memory)...

see https://www.volvoclub.org.uk/faq/Fue...sure_Regulator for more info. I don't recommend the tire gauge method they mention.

 

your pressure could still be off. I know you said you checked the FPR vacuum line and saw no leakage, so that means the diagram isn't ruptured, but the regulator could still be misbehaving. a simple fuel pressure test will eliminate this, or tell you that you need a new FPR. IF the pressure is good, then I'd look at the injectors, or at least check for wet spark plugs after cranking 20 seconds on, 10 off, 20 on, then pull a plug as quickly as you can. wet plug == fuel flow.

 

Thanks again for all the suggestions. I'll try the FPR test this afternoon when I get home from work. Unfortunately, a fuel pressure gauge I borrowed from a friend doesn't have all the fittings I need, so I might rent one from an auto parts store.

 

Never seen an FPR cause a no-start unless fuel is pouring out of it, never seen that either.
Did you check the injectors? A car sitting for a long time may have fouled them up.

 

I was kind of thinking the same thing. Unless the FPR is causing the intake to get excessively overly enriched, it should still start. I'm actually close to getting the fuel rail pulled to see what my injector spray pattern look like. The car did pass the noid light test on all four wire terminals on cranking.

 

I finally got around to testing the fuel pressure at the rail. Since the vehicle can title, I tested for the highest value while cranking. I was able to get it up to about 42-42.5 PSI. While I was at it, I tested to see if fuel came out of the vacuum hose on the fuel pressure regulator, but I didn't get any. This test was performed without power to the injectors, since I was just testing pressure received at the rail. Unfortunately I had to do a MacGyver job of getting the tee to work with the flare union on the supply line to rail, so it leaked off access pressure fairly quickly afterward, about several minutes.

At this point I'm considering the possibility of faulty or plugged injectors. I'm going to remove the rail from the intake manifold and reinstall the grounds and see what I get for a spray pattern.

 

That's what I'd do at this point.