ben long time since mechanic work

[i8uiky]

my mothers car is giving her trouble. 1998 cad sedan devill It cranks for 20-25 seconds or more and will backfire a few times just before starting. after it starts it runs perfect and starts normal for the day. I havent had a chance to look into it yet and was stabing way in the dark with some ideas like the low rpm circiut in the controle moduel being defective. maby fuel pressure regulater. it has a new fuel filter. service engin lite not on. I should have a chance to look tomarrow. any ideas of what I can look into?

thanks in advance
i8uiky

[EzyStvy]

Maybe a timing issue? But then you'd think it would run rough after it started..

[rjfvillarosa]

That sounds like an air leak on the inlet manifold, the leak is making the mixture lean hence the long cranking time and back fire, once it starts the alluminium of the manifold will expand very quickly with the heat and reduce the air leak to a minimum.
With the engine running, spray some WD40 (releasing oil in a pressurised can) around the inlet manifold to cylinder head gasket, if you get a change in exhaust note or a slight missfire it means for a split second the engine was running on a mixture of petrol and WD40 where the WD40 had momentarily been sucked into the manifold by the air leak.

[i8uiky]

great idea I'v used that test before so I know what you are talking about.
I did'nt get a chance to check it out today but I got one of dads trucks to run perty good it needed a new fuel injecter and now I need to fix the other farm truck so it runs good hopfuly I will get a chance to check moms cad tomarow. Does anybody have any other ideas?

[RevCLB]

This may sound stupid but I have had experience in the past with starting problems. Sometimes just making sure the battery posts & clamps are completly free of corrosion can make a world of difference. Even a slight gray cast can restrict current flow. Lil Jimmie could give you a better tech explanation but cleaning & polishing these has helped me in the past.

[i8uiky]

Originally Posted by RevCLB This may sound stupid but I have had experience in the past with starting problems. Sometimes just making sure the battery posts & clamps are completly free of corrosion can make a world of difference. Even a slight gray cast can restrict current flow. Lil Jimmie could give you a better tech explanation but cleaning & polishing these has helped me in the past.

revclb that exact thing happened in my 1971 chevy pu. as for my moms cad it cranks fine. thanks for sugesting it though

[i8uiky]

Originally Posted by EzyStvy Maybe a timing issue? But then you'd think it would run rough after it started..

timing is at 3 degrees when cranking then will verry do to driving conditions. and its a distributles ignition system(dis).

Originally Posted by rjfvillarosa That sounds like an air leak on the inlet manifold, the leak is making the mixture lean hence the long cranking time and back fire, once it starts the alluminium of the manifold will expand very quickly with the heat and reduce the air leak to a minimum.

the manifold is some kind of plastic I tried spraying around it while my dad cranked and it di'nt help it start any better and I sprayed with it running and no change in rpm. the bolts are all tight. as for it back firing I think during the cranking the fuel builds up in the manifolds and when it starts to fire it backfires a little bit


is their some kind of a control moduel. I know the dis gets a signal from a magnetic pulse on the crank shaft but does the main computer control the spark or is their another control. I was thinking sometimes a controller wont work till they worm up enough sometimes they wont work when worm. Im going to check for spark in the morning when cranking.

I checked fuel be for start with key on and their is plenty of pressure.

thanks for the replies
i8uiky

[BigRed CC Dually]

Originally Posted by i8uiky my mothers car is giving her trouble. 1998 cad sedan devill It cranks for 20-25 seconds or more and will backfire a few times just before starting. after it starts it runs perfect and starts normal for the day. I havent had a chance to look into it yet and was stabing way in the dark with some ideas like the low rpm circiut in the controle moduel being defective. maby fuel pressure regulater. it has a new fuel filter. service engin lite not on. I should have a chance to look tomarrow. any ideas of what I can look into? thanks in advance i8uiky

I would suggest that you take the car to an AutoZone or similar store and have the codes read for free..a 98 should have OBDII and even though the CEL is not on it does not mean that there is not a soft code set. Any codes retrieved will help with a diagnosis.

[i8uiky]

I forgot to say that earlier I have a scanner and checked codes already and their are no codes.

one thing I did notice with the scanner on is one of the o2 sencers had no crosscounts and was lean.

[g35coupe]

before she goes out in the morning, after it has been sitting for a while, take a hammer and tap on the starter. then, try starting it up, if it starts right up it's your starter. if not, sounds like a vacuum leak. the backfire sound is from the extra fuel that has been dumped into the cylinders

[lil Jimmie]

I don't know what the car has for sure but look at the crank sensor and cam sensor <--- if it has one. What happens is with the temp change something is not making contact and once it's warm it's fine. This could even be the ignition switch or an internal problem in the ignition module but really there could be a number of things even the engine temp sensor (not the idiot light). A loose wire harness to the DIS or fuel injectors could also be something to check. Ensure all engine grounds are ok.

[i8uiky]

It has spark when cranking.
could the fuel pressure regulator not hold pressure during cranking until it gets enough vacuum? It probably wouldn't flud the engine and make it backfire if that where happening. A good friend was telling me theirs something with the fuel pump but couldn't remember exactly what it was, just that they start doing weird things just before going out on late 90's GM. I'll try to check the pressure during start up.