Hello Everybody, i've read these forums for a long time, first time posting. I have a 97 volvo s90, recently the headgaskets been leaking and im planning on tackling it by myself this weekend. I've been having a crank no start issue aswell, im wondering if its due to the headgasket not sealing the combustion chamber correctly and not allowing compression to build. It almost seems like the starting issue arrose before the gasket did but its hard to say for sure. I just spent nearly 800$ getting the ol girl out of impound for registration and this is with knowing about the issues, my friends and family think im crazy for even getting her out, but they've never owned a Volvo I guess. I love my car, and I dont think id be happy in anything else, so i'll do what I have to, to keep her on her feet. I just changed the following, crankshaft sensor, cam sensor and seal, m.a.f., all the pcv hosing and boots (still have the old oil catch, hoses arent connected) spark plugs, coil packs (insulation crumbling a bit near connections so i cleaned them up and secured them with electrical tape), and battery. The engines getting spark, and when I press the schrader valve on the fuel rail, gas is there but its not a spray, it more or less pours out into a dribble and I can hear the fuel pump priming when i turn the key. Ive poured a teaspoon of oil down each of the sparkplug wells and pressed the pedal to the floor while i cranked it and it the engine cranks normally then gets faster and faster till it feels like its spinning pretty fast. It feel like its just on the very edge of starting, like if it had a little tiny boost of energy or something it would start, but it doesnt. Ive tried with a fully charged battery and before i charge it up again and give it another shot, im wondering if my repeated efforts at this will do more worse then good?. Im leaning toward fuel pressure regulator needing to be replaced, ive swapped out ignition and fuel pump relays and have checked a the fuses, im stumped. Any ideas, input or suggestions are welcome and greatly appreciated...thanks.

Side notes...
A few months back while trying to start I heard pop under the hood. Upon inspection i found the engine had backfired, but instead of leaving thru the exhaust, it came back out the air intake, shattering the m.a.f. sensor while blowing my airbox into pieces.. yikes
-Two of the new plugs already built black dryish carbon looking deposits on the tips during 1,...15 minute drive.
-Fuel Regulator vacuum line smells faintly like fuel.
-before the crank no start, car would idle extremely rough and seems excess smoke would come from under the hood where i disconnected the pcv hoses.
-smoke from exhaust is white not blue, will go away after 15-20 minutes.
-i do have the air intake mod, recently seems the air filter a tiny bit damp but not bad at all.

 

The head gasket might be the root cause of not starting. If you think it's cranking "faster than usual" then that is suggesting you've lost compression on one or more cylinders. It's possible to lose compression on all of them.

 

Well, technically a backfire is through the intake, if it is through the exhaust it is properly called an "afterfire". (aircraft mechanic here, and this can help you pinpoint fuel mixture issues).
FWIW, my 960 did the same thing, endless cranking to start. It also had a leaking head gasket, but was still driveable. It also backfired through the airbox, shattering the lid.
Mine seemed to be related to the cam position sensor. If I cleaned the connections, it would generally start right up.
And the head gasket is longer than a weekend job. You will need to send the head out to get shaved to ensure it is perfectly flat before you put it back together. Otherwise it will leak again very quickly.

 

Thanks for your replies, Ill take the cam sensor back off and clean the connections again. How would i be able to spot the cylinders that are losing compression? Is there anyway to tell by checking the plugs? I have maybe a hundred bucks left this month to put towards getting the ol girl up and running again, is there anyway i can make a leakdown tester with a bike pump.?

 

It feels like its cranking real sluggish when i first turn the key, but as it cranks it starts spinning faster and faster.... uhmmm imagine trying to spin a bike tire while squeezing the brakes, then slowly letting off the breaks while still spinnig the tire until its spinning as fast as you can get it,, then it spins for few seconds like that and finally starts.... sorry if that doesnt make sense, its the best way i could describe it.