I'm really stumped with this no start problem.
Everything checks out- the RSR is good- (a new one at least), the RPM sensor works, no vacuum leaks, timing is on as per the timing belt replacement procedure, the AMM is working, IAC and power stage are good- I only have a multimeter, but I checked everthing for ground and continuity and it all seems okay.

The injectors show infinite resistance, when they should show 16 ohms according to the spec book- but they squirt fuel into the cylinder. So the Fuel pump relay works.. it makes a good healthy sound when the key is turned on. When I disconnect the fuel line fuel squirts out all over!


I'm wondering if the ECU has gone kaput? the Bosch # is 0280000556
When I try to bring up the OBD is shows everything as working- in mode one, but can't get any readings in mode two or three-

the engine gets fuel and has a healthy spark =it just won't fire- it backfires and coughs. otherwise it just cranks with no intention of firing- plugs are new
and I changed the copil too..

any good mechanics out there with some fixit solutions?

Do you have access to another ECU? The 556 ECU means you've got a California car - with EGR - but a 561 or 951 will work for a test.

I had a problem with an 89 740 a couple of years ago - fuel seemed to be pumping fine out of the line, injectors were working, good spark, no start. Turned out to be a bad main fuel pump which was failing but not quite dead, and not up to specs on pressure.

Look in the 700 FAQs for fuel pressure testing, might be useful.

that's something to consider-
although the fuel squirts out with vigor!
I can hear the relay and the pump working-

but the info on the ECU is good- I'm hoping that it is the ECU and that will be the end of it-

when I check the OBD, the computer works the first time - then it quits- won't work again-
always shows 1-1-1 which is good I suppose

One other simple thing to check - firing order. The alignment of the plug wires on the rear mounted distrubutor is easy to mis-read and swap #1 and #2.

That can cause the symptoms you describe.

Rear distributor: Left-to-right terminals are 4-3-1-2

Left is passenger side, right is driver side - go to the following site and move your mouse pointer over the drawing of the distributor for a picture.

http://www.vlvworld.com/indexframe.html?VolvoRepairManual/700_2_9.htm


Plugs: Front-of-engine-to-back: 1-2-3-4

I didn't mention your name in my reply but thank you for the SIMPLE solution!!

You were meant to come to my aid!!
I checked out your links and they led me to the right place --
I did have the firing order messed up- I knew it was a simple thing-
and thanks to you and your advice it fired right up

4-3-1-2 is the right order on the dist. 1-3-4-2 is the correct firing....
I had it set up @ 2-4-3-1 on the dist. and 1324 firing- wow!!


my neighbor suggested that about two weeks ago but i didn't listen! hmmm!

hard head da kine!
Thanks Thanks

I can't find the firing order of this particular engine- I didn't change the order of any of the distributor wires (that I can remember anyway) and the engine has started with the current firing order - 4-2-3-1 (facing the radiator left to right)or 1-3-2-4
I have read that the firing order is 1-3-4-2 but that doesn't work.
dist. turns clockwise-so when #1 fires the rotor is on #1 plug, (even with the edge of the valve cover-)...

From top post:
"So the Fuel pump relay works.. it makes a good healthy sound when the key is turned on. When I disconnect the fuel line fuel squirts out all over!"

Don't be misled by the pump running when Key is turned on. That's not the same ECU control as required for cranking and running.

But it will instantly build enough pressure for the "squirts" you are seeing.

Try feeling the relay when you turn the Key on, so you'll know what it feels like when energized. Then feel it while you turn the key farther to crank it over. You should feel that same "click" again as the cranking begins.

If no click while cranking, that's a problem. But right now I can't imagine what part of the Timing Belt job could have gone sideways on you and cause a relay control problem.
--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

I took the cover off the relay-to watch what happens when the key is turned and the engine cranked. When the key is turned on the relay connects on one side and releases, and the other side connects and remains so.

Sounds like your ecu may be bad. The ecu of that year was problematic. You could try swapping it with another good one from a PNP. OR buy one online.

BTW did you check the fuel pressure regulater? Could be causing a rich mixture.

Are you getting compression? Maybe the timing belt is broken?

very good compression..
just changed the timing belt-

Have you tried jumpering it? Even though the battery sounds good, volvos are funny and won't start without a good battery.
Also, if you have fuel,spark,compression. All thats left is spark at the wrong time. If you have a timing light, put it on #1 and crank it over. You should see 12degrees BTDC.
--
Post Back. That's whats makes this forum work.

timing is good-
the battery is charged too- the starter is healthy

there must be a short in the electrical some where- or the ECU is bad-

that's all I can think of