Car has sat for 6 days, one week ago I noticed it took about 20 seconds of cranking to start and now after Christmas vacation she wont start! What're some things that would cause no tach signal? When cranking, the tach will sometimes bounce.. Cannot get rid of this intermittent issue. Has anybody had problems with the ignition control unit? Replaced the crank position sensor 3 times in a year and a half. Along with the radio suppression relay and many more things... I noticed this wire at the crank position connector when pulling back the cover. I really need to get this figured out as it's been a problem for almost 4 months out of this year..

92' 740 Regina

 

Peel back that insulation and see if there are problems down the line, that would cause issues with the sensor.

What brand sensor are you using? Three in a year is way too many, may be that wiring is fouling things up including the no start you have now.

If not the CPS, I'd look at the fuel inj. relay.

 

Has a new RSR, used fuel pump relay just swapped in, new fuel pump, new fuel pressure regulator, new distributor and coil. Also that black wire at the CPS connector appears to like that the further I cut the insulation back? All I know is that I got fed up a few months ago and took the car to a nightmare shop where they threw a bunch of parts at it without my permission at first, and in the end they "discovered" that all it needed was an "oem" cps and then it ran fine for a couple months after that. When I pulled the CPS out today to inspect and clean, it looked like just another cheapo. I guess what I'm really trying to figure out is if my ECU, ignition control unit, or ignition amplifier could cause this issue and cause the no tachometer signal before I purchase a real CPS..

 

these 'new' parts, are you getting them from a Volvo dealer, or reliable sources of quality volvo OE grade parts, or from fleabay and/or bigbox autoparts stores ?

 

Get an OEM CPS first. Go from there but check that wiring too.

 

Most of the time I go through napa when it comes to parts, which I guess is OE grade & better than autozone.. Just put in another crank position sensor, waiting for a jumpstart and we'll see if it was a faulty CPS that decided to quit in just a week of sitting? Hope so at this point..

 

NAPA is no different than AZ and all other of that type. Good for oil and fluids, nothing else brand specific.

 

I think I've got a wiring issue, I changed the CPS with no difference. When trying to start the tach still wouldn't move, I decided to tap the rsr a few times and move it to another location in the bay a little and then the car barely started up. Now it is sitting at an idle as I charge up the battery.. I may just order a rsr plug housing and see if that makes a difference

Corroded RSR, old picture and has a new rsr. Contacts were cleaned up the best I could.

 

I let it warm up and turned it on and off probably more than 10 times, the tachometer moves when turning the key now... The last couple tries it stumbled and almost died on it's own but managed to stay on. I'm going to let it sit for awhile and try to start it again soon. Seems to idle like a volvo with 300k but it's close to steady

 

Went to drive it down the road, all normal until it started to stumble really bad and have zero power same symptoms back in September. Was able to start it up again and luckily limp it back 20 feet.

 

Next day, wont start & no tachometer reading. I've ordered a white label siemens ECU identical to what I have in my 740. I'm thinking that maybe this intermittent issue underlies with that computer.. If that doesn't work, I'll replace the ignition control module attached to the coil and also replace the ignition control unit under the steering wheel. If all else fails, I'll have to assume there's a wiring issue. Posting all of this in hopes that I can get through it & help others figure their similar symptoms. Surprisingly with all the research I've done on this I cant find any real stories on this. I've replaced so many other items and checked all fuses so I'll have to hope the ecu will fix this...

*Breaks down* *runs again* *lady runs a stop sign into the volvo bending the rear axle* *rear axle gets replaced and then breaks down again*

 

I'd just assume it's a wiring issue right now.
You are replacing too many parts without having a clear diagnosis. ECUs rarely fail.

 

I'm gonna have to assume it's a wiring issue, havent tried the used ecu I purchased on ebay yet but I was able to get ahold of a ignition control module today (attached to the coil), and still no start so I installed the old one and returned the part haha. Another Volvo owner told me that fuel ecu's can sometimes fail which is why I bought one..

 

have you verified the coil pin 15 is getting voltage when the ignition is on?

 

I havent, need to get a multimeter. Terrible with electrical, hence why I've been throwing parts at it in hope's that it'll be magically fixed lol...

 

Timing belt tensioner failed
Feeling pretty dumb! At least I found the culprit... will get it back on the road this week lol...

 

How did it fail? The picture doesn't show a problem as far as I can see.

 

I'm not sure what happened but timing is definitely off

 

What makes you think you have a timing problem? Things don't look too bad in the pix.
That white mark you point to doesn't mean anything.

 

I can't see the TDC mark on the crank shaft there at all. the TDC mark on the camshaft is off by 3 teeth but that doesn't mean anything unless the crank TDC is spot on. and yeah, those white lines mean nothing. the intermedia shaft doesn't matter if you have a camshaft distributor, but it DOES matter if you have a side distributor (740's occasionally came with a side distributor). the accessory v-belts don't matter at all.