Is there something I can spray into the air intake system to see if my car will start and test my theory that my gas is no good?

If so, what should I use and at what point in the intake system should I spray it?
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1993 240, 1992 240GL, 1985 240DL Wagon, 1983 240DL

The throttle plate is probably closed at idle so spraying starter fluid ahead of the throttle may not work. Try pulling the hose that goes to Idle Air Control valve and spray starter fluid in there.

It would be preferable to drain the tank and flush the fuel line to the injectors. Bad gas isn't going to help with the starting.
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1980 245 Canadian B21A with SU carb, M46 trans, 3:31 dif, in Brampton, Ont.

There are 2 hoses that go to the IAC. Should I spray in the hose, if so which one, or into the IAC itself, if so, which side? Thanks
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1993 240, 1992 240GL, 1985 240DL Wagon, 1983 240DL

Sorry, It's my sister's '89 that I've worked on and don't recall the plumbing.

But air is routed from before the closed throttle plate through the IAC and back to the intake manifold, bypassing the throttle plate. So wherever the return hose connects would be a good input place for starter spray, if it is accessible.

Preferably in the throttle body area so that the spray is evenly distributed to the cylinders. Maybe even the port that connects to the Fuel Pressure Regulator?
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1980 245 Canadian B21A with SU carb, M46 trans, 3:31 dif, in Brampton, Ont.

Spray a little starting fluid into the intake tube behind the air filter.

Do you have fuel pressure ?

Greg

I would not spray there, you might damage the AMM.
I would spray after the AMM.

Joseph

Yes, I have fuel pressure and here is why I suspect bad gas. The symptoms my 92 are experiencing are the same symptoms my 83 experienced. Both of the vehicles are not used, however started weekly over the course of the past 3 years and run for an hour. The 83 hasn't been able to start in a year, will crank, but not fire up. Prior to this it would start and run really rough(no, it's not a bad AMM) and eventually would not start at all(cranks-does not fire up). Now, 1 year later my 92 is experiencing the exact same symptoms! That's why I am thinking bad gas. I have put fresh gas in the tank over the course of the years and run them every week. As they run rough, they also have some backfire occurring. I did a fuel output check on my 83 and it is pumping out the amount specified in 30 seconds of cranking the engine.

I will try the starting fluid and see what happens, although any other ideas would certainly be appreciated.
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1993 240, 1992 240GL, 1985 240DL Wagon, 1983 240DL

Where are you located near. I am at Coors and St. Joseph's
in ABQ.

Joseph

Located Far NE Heights
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1993 240, 1992 240GL, 1985 240DL Wagon, 1983 240DL

Have you checked your timing belts. Take oil cap off and
while someone is trying to start the car see if the
tappets are moving. If no tappet movement then your belt
is broken.

Joseph

Yes, have checked belts. See movement with gas cap off. Because the 92 is experiencing exactly the same symptoms as the 83 did, I am leaning towards the gas?
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1993 240, 1992 240GL, 1985 240DL Wagon, 1983 240DL