there's no choke, just the throttle plate in the throttle body. As the link above explains, with the Idle air control circuit mechancially disabled (via closing off the idle air hose), a warmed up engine with no load (AC off, lights off, in neutral or park) should barely idle at 500rpm in neutral. the ECU uses the IAC to bring the idle up to 700rpm and maintain it even in gear and/or with the AC on. It only does this when the throttle position switch indicates the throttle is at idle.

if its not working right, I would remove the throttle body and idle air control valve, and thoroughly clean them with throttle body cleaner spray and a toothbrush, and inspect the IAC hoses for any signs of cracking or hardening, and replace them if needed. The IAC is a solenoid driven air valve, with no power its closed/off, with power, its open/on... normally the ECU pulses it to partially open to maintain the RPMs.

anyways, after cleaning, replacing any cracked hoses, and reassembly, THEN go through that adjustment procedure linked above.

 

Hi. These are my no-start symptoms exactly (from Matthews): https://www.matthewsvolvosite.com/fo...85e66d#p424174

The car died on the road because the ground wire came out of the back of the IAC connector. Fixed that but now I cannot start. This car was having hit-or-miss starts before and coil replacement seemed to do the trick, but after replacing it again (after finding weak/orange spark) no difference. So now I think I am looking at the timing belt, that is, at the tensioner (belt looks quite new and healthy and is also Volvo). But I've looked and it seems hard to find online a simple/clear explanation of whether or not my belt has slipped. Can you help?

Also, am I going to have to get this car on blocks and get new tools and pull everything apart to deal with the tensioner? I'm not lazy but I need to know whether or not to put this on the back burner right now.

Thanks for any info/perspective.

 

remove the timing top cover, and if you shine a small bright flashlight down into the lower part of the timing cover, you should be able to see the crankshaft pulley... turn the crank over with a wrench until the mark on the pulley lines up with the marker on the block, then check the camshaft position. if its a 240 with a side distributor, you also need to check the aux shaft, that too has a timing mark, but a 740/940 with a camshaft distributor, the aux shaft timing doesn't matter.

 

Hi pierce:

Very glad to have you on the line. I'm always grateful when you show up on a thread (other favorites of mine: @Lev, @Tech, @swiftjustice44).

If I may I wanted to get your take on what my only-Volvo repair guy had to say about my timing belt (I hope I'm relaying this faithfully):

1) Unless the belt suffered some major trauma, it didn't slip, and given the square tooth probably is not slipping, not to mention the engine in my 1990 Volvo 740 GL is a non-interference engine. (The inside of the cover also doesn't show any signs of friction/sliding off, and the tension at the tensioner seems fairly high, so maybe I'm actually posting on the wrong thread here?) So he doesn't think a slipping belt is my no-start culprit.

2) Don't go by color of spark (e.g., orange). If it's pulsing and jumping a 1/4" gap to a piece of metal (which it is; have also confirmed RPM sensor is working), that's good enough spark. (I do have a tiny voltage drop at blue wire going into coil, of about .05V, but I'm guessing that's not significant.)

He wants me to pay for AAA Plus and get it towed in. (Of course he does?) He thinks a fuel pressure gauge needs to be placed inline to see if it's delivering enough fuel pressure. (There's no port on the fuel rail.) But back when I popped off the new FPR I bought (and it did POP) to try putting the old one back on to see if it would change anything (ignorant, flailing, trying any f*cking thing), fuel was actually spraying out past the deteriorated O-ring while cranking so, I don't think it's fuel pressure, but again, I'm ignorant. (I also don't think it's water in the gas; I've brought the tank from half-full to full with a gas can and it hasn't helped the car fire up one jot (it consistently cranks however).)

I'll be honest, I'm close to quitting on this. Not to mention that I don't even have a socket big enough to turn the crank to see how marks line up. That might sound lame/lazy, but this whole adventure is a sidebar for me that I'm hitting a limit on (re: time, money, patience). If I could have someone to go back and forth with here I might be able to go on, but I feel it's becoming disproportionate. My daily driver is a 2004 V70, rock-solid workhorse at 270K. My commitment here was partly aesthetic and partly out of hating to waste this beautiful machine which is likely good for many more miles; I thought it was worth getting down to the "one thing wrong" (to quote Lev). For a while I was sure it was a ground fault or some other wiring problem that would turn out to be the reason this car was always a hard/hit-or-miss starter, though after the coil was replaced after taking it in for this issue, it seemed to start more reliably (though misses would still occasionally occur). I still have a hard time "striking spark" when trying to jump it. But again, I'm nearing the end.

Hoping to get more perspective from you on this. Again, thanks for being there.

PS. On the air side, throttle body clean, TPS working, MAP sensor not throwing code (though that slender hard plastic hose looks like sh*t; all other hoses look healthy). IAC valve clunking on diagnostic pulse, but I am in fact only getting 4 ohms between ECU pins 9 and 33 and swiftjustice44 has said on an IAC thread I came across that it should be more like 8?...)

 

Why are you questioning the T belt? If the teeth are solid, and there is tension, there is little chance of it being the problem.
If the car ran before the IAC connector problem, and not run now, it should be something related to that, probably electric.
Fuel or spark? Spray some starting fluid in the intake, see if it fires up, then you know. You tech doesn't inspire much confidence.
At this point there is Too Much Information, focus on the basics! When it comes down to it there is little that hobbles these cars but certain rules and procedures have to be followed and a bad mechanic only messes things up--seen it many times and have bought many a Volvo on the dirt cheap after the owner got bamboozled by a shop and gave up.

 

Hey Lev:

Thanks for replying.

Yeah, TMI. Erred in that direction rather than giving too little. Giving only the pertinent information would probably be best, but it seems like I'd need to know what's going on here to do that.

The car had sat for a good while even before I started looking at it, and even longer before I finally figured out the IAC connector problem. Gas corruption in the meantime? Is that what starting fluid is supposed to overcome? (This is how little of the "basics" I know. I did find out by reading the can of starter fluid that you don't spray while engine is being cranked. So that's good.) But like I said, I added a half tank of good gas to the half tank of bad... if there was water in there, wouldn't I have affected the dilution/corruption enough to make a difference there? (Again, completely ignorant.)

Also, for all the info I provided, here's a bit of context I didn't: After restoring signal to the IAC, the car had its only successful steady (20 min) idle it had ever had since I started work. BUT it was many start attempts between restoring signal and finally successfully firing up, and many no-success start attempts after that. I maybe should have hopped in and given it an Italian tune-up once I actually got it going instead of turning it off to see if I could repeat my success. But if I had that one success, does that mean I can rule out slipped belt/misaligned rotor? (Again, diagnostic comm tells me RPM sensor is OK.)

Again, thanks for weighing in.

PS. Only questioned the T belt in the first place because it seemed like my no-start symptoms mapped onto the experience of that poster on that Matthews thread I linked to. Again, ignorant, casting around desperately.

PPS. I told pierce I wasn't sure I had the patience to even shop for the right size wrench socket to move the crankshaft to see about timing marks lining up. But I did, and while I haven't for the life of me been able to spy the mark on the crankshaft pulley so as to line it up with the mark on the top inside of the timing belt cover (it seems from the diagram that the mark is on the face of the pulley, which face is against the lower cover?)... but I took a tip from act1292 (from a different thread) and removed the distributor cap to see whether the rotor was pointed at either #1 or #4 after lining up the mark on the camshaft pulley with that top mark, and it seems that the rotor is indeed pointed at #1, though I really can't tell if it's exactly on point...

 

So, it ran for 20 mins and then no more successful starts?
Seems to me that something, most likely of electrical nature, went bad. No, not the Tbelt.
Also possible, some fuel obstruction since car sat for a time.
I say spray starting fluid in the intake to eliminate a fuel delivery problem: loosen then undo the intake hose, spray the fluid for 3 seconds, put the hose back on quickly, no need to tighten the clamp, crank the engine. If it fires up for a couple of seconds you know you have a fuel problem, if not, spark problem. Make sure the battery is strong. Go from there.

 

Well...... starter fluid made the poor old girl wanna try.... putt putt but no vavoom... then a POP (and brief burning smell) after trying to go again immediately after first crank with fluid... consistent putts/coughs with each subsequent application... when I finally thought to give it throttle the POP was so big that it blew the intake hose from IAC to manifold (behind throttle) right off (biggest stink also), perhaps due to pooling starter fluid in intake hose (I was draining it repeatedly)?...

....so, an effect was had. (And yes, battery is good, have confirmed it only dips to 10.7 volts on crank. Spark plugs were also pulled and cleaned, finally; they were a bit scuzzed and also the plug coming from #2 seemed a little wet?...)

Am I now on the hunt for faults in fuel delivery/pressure/et al.?

Feels good to be zeroing in maybe. Very grateful for your help. (Further coaching would be very much appreciated...)

 

Careful with this, don't spray too much fluid, it is highly flammable!
Not sure about the mini explosions you had; did you get a couple of seconds of actual engine running?
This is a Regina I take it, one fuel pump? How long did this car sit unused, wondering about the condition of the gas in the tank and possibly other contaminants?
The ignition parts in this case (car sat unused) should be renewed, especially the plugs, make sure they are indeed not contaminated, and gapped correctly, .28-.32.
BTW, whereabouts are you? (weather)

 

Hey

Yes, I was worried about being too explosive, that's why I kept draining the pooling starter fluid in the intake hose (at least I'm pretty sure it was (mostly) the fluid?)...

So you don't think the mini-explosions were due to the pooling starter fluid? I did have several backfire-type events when trying to start the car while the IAC was still disconnected (before I found that ground wire break)...

No, no actual engine running. Just some moments where it seemed it might fire up (as opposed to just the old wawawawawawawawawa of the impotent cranking)...

Yes, Regina. Has been sitting now in one spot since February (in upstate NY; the frost is on the pumpkin...).

I did clean plugs, but now I'm wanting to check them again to see if they're wet... (no idea about the gap measurements, but they are Volvo...)

PS. Have used diagnostic comm to confirm TPS and RPM sensors are good; also have signals to/from fuel pump, fuel injectors, IAC and RSR (also no codes being thrown from either fuel or ignition side, i.e., socket 2 or socket 6)...

UPDATE: Pulled a plug to check it for wet, seemed dry, but not a trace of the scent of fuel on it, only of starter fluid... and now when I crank, starter fluid is all I smell under the hood, whereas once upon a time I used to smell fuel, though it's actually been a while since I smelled that. Did my fuel pump gradually die? (At the risk of making your eyes roll, my only-Volvo guy said "It's never the fuel filter." But might it be???....)

 

Oddly, I too say "it's never the fuel filter"... Well, only if it's under full power and there is obvious starvation then, I never change them "just because".
Your engine should have fired and ran momentarily with the ether, so I don't think your problem is fuel, so spark then, something electrical. I'd get some new plugs, just cheap copper NGK, gap them .28-.32, and try to get at the spark issue. How's the crankshaft sensor?

 

Hey

I will look into new plugs, but since I've already confessed to my ignorance I'll go ahead and ask a dumb question: If my plugs were not good, how was I able to run the one time I was able to run? Did I manage to overcome the too-large gaps somehow? But then how was it starting prior to the IAC failure that immobilized it in February?

Also dumb question: Is the crankshaft sensor the RPM sensor? Because the diagnostic comm indicates that sensor is good. (Is there another test?) Though I guess my question there is the same: If that sensor were bad, would I have been able to run that one time?

I have actually wondered at times whether there might be a draw on the whole system somewhere that is leaking juice away from starter and/or coil (again, ignorant), which fault perhaps I was lucky to overcome that one time? But voltage (and ground) are both good at the coil and all wiring continuity to and from ECU and ICU is good. How does one know if one has a bad starter? (No screeching/grinding noise from starter, and contacts from battery are clean.) Battery is also strong; I have confirmed it has good ground to chassis, but might there be a ground fault somewhere else (my grounding straps to the manifold are good, where else might I check)?...

Finally is it possible that I don't have adequate voltage at the pump? My last voltage test showed 12V kicking on then off with relay (red probe to pink wire at connector in trunk, black probe to brown/earth), then about 10.5V while cranking. (Swapping out relays makes no difference.)

Thanks again...

IMPORTANT UPDATE: Read somewhere that popping off the hose from IAC to manifold when cranking (as was happening last night with first application of starter fluid) is due to misfire. Turns out I had reconnected distributor cables incorrectly after replacing distributor cap after checking position of rotor when I was still in doubt about T belt. Correctly reconnected cables, then reapplied starter fluid. It ran, for about 2 seconds, then died. Pulled the FPR to see if I could see any fuel falling out of the rail, nothing, and only a few drops fell out of the FPR. Put the FPR back inline. It is now (thanks to cleaning the spark plugs? idk) back to a familiar pattern of briefly firing up once (like half a second), then cranking and cranking to no avail, then repeating pattern after resting for a time (am I burning off the fumes that accumulate in the interim?). Do I have a fuel problem after all? Might pump be losing power somewhere else, or might it just be crapping out? Or am I simply struggling with gas that has gotten more and more worthless? (Is it worth trying to get that fuel filter out after all? It does look like sh*t...)

Again and again, thanks.

 

Well, OK, so wires are correctly installed, fires up with fluid, then we are back to fuel problem likelihood.
Your may be fine but it's a cheap way to eliminate the possibility, they get contaminated when chasing problems like yours.
Yes, RPM is CPS, should be anyway, what else would it be?
Check the fuel quality, look at the fuel filter (in this case)...
I wouldn't be getting into too esoteric electrical issues, not yet, anyway.

 

Would love to make progress on this ASAP, as I am having anxiety about possible water in gas having already damaged the pump, but I am reading that there is no drain plug for the tank in my Regina 740? How do I access/inspect/drain the gas? Still can't budge those apparently-rusted-solid connections at the fuel filter (have applied B'Laster once again, or rather B'Laster-soaked rag-bandages), which filter is itself entirely rust-colored, all of which is increasing my anxiety about ruinous rust in the fuel system...

 

Sadly there is no way to drain the tank completely short of removing it. You are in a rust prone area though don't assume that there is rust/water in the tank.
Removing the fliter at this point is a good idea, the surface rust is a pain no doubt, can't offer much advice there. You can also try to open the fuel line at the motor and see what comes out when you crank it, if anything, to confirm.

 

OK I'll see if I can finally free that filter.
Will also check fuel line after giving B'Laster some time to loosen that 17mm nut connecting line to rail.
If I do get the filter off, will that drain the tank (mostly)? That is, should I be prepared for a rush of fuel from the tank?

 

Fuel line is tight on purpose, you have to unscrew the fitting, it's not pressure fitted, use well fitting wrenches!
If you remove the filter, fuel won't come spewing out, you'd still have to pump it out energizing the pump... At least you'd get some idea about what the fuel looks/smells like.

 

Just to reassure: I did discover the fitting upon second look (first look was with the unseeing eye of an even-greener newb than I am at present), and I do have a properly fitting (17mm) wrench.

(UPDATE: I can now see that I need to grip that 14mm fitting on the rail itself while gripping the 17mm fitting on the line, and right now I only have a wrench with 14 on one end and 17 on the other. So many fun twists, no pun intended.)

Will write again when I have more to report after busting more rust. Thanks for standing by.

(UPDATE TO THE UPDATE: Freed the fuel line. Stuck it in a dry beer bottle. Cranked. Three 1000s, four 1000s, eight 1000s. Result: Bottle remained dry as a bone. So, there we have it. Once more into the breach. Meaning diving under the car to attack those fearsome-looking filter connections once again. BRIEF GEEK-OUT: So cool how the jack for my 2004 V70 also works on this 1990 740. Because Volvo.)

 

Fuel filter off. Drained fuel inside into jar. It fell out freely, so yeah, doesn't seem like filter was stopping flow to motor. But the color--to say nothing of the black gooey edges of the puddles on the driveway or the black goo apparently sprayed on the underside of the car all around where the filter sits in that saddle--has this newb fearing the worst. (No little "globs" of water at the bottom of the jar, however.) I'll be putting filter back inline and trying to fire up in the morning when all the fumes from my splashing are gone. Feel free to allay my newbie fears in the meantime, however. (Also any instructions on what my "fire-up" procedure should be after replacing filter would be appreciated.)

 

thats some nasty fuel, for sure.