My '93 Seca RV Starting issue

[Rex Greenland]

I own a '93 Carolla Seca RV (1.8ltr, auto) which I love dearly and runs beautifully, but only once I can get it started!

When I turn the key to start the engine it will start briefly and then stop again. If I do it repeatedly it does the same, except sometimes it will spark into life and purr like a kitten. This lack of reliability has detracted greatly the joy of me owning this car, which is a joy to drive.

I have been under the the misguided belief that it was a Mass Air Fuel (MAF) sensor issue and have bought cans of the MAF fluid trying to spray clean all of the electrical components that look like it, only to discover recently when I tried to buy a new MAF from Toyota that this model does not have a MAF. But the issue persists and is in fact getting worse. I can sometimes get the engine to run if I spray a jet of the MAF cleaner fluid directly into the intake via the small port/tube directly above the accelerator butterfly valve and have actually removed the accelerator b/fly valve assembly, dismantled it and cleaned it, but no joy.

I am at the end of my wits and suspect it is possibly one of the electrical components that sit around the fuel intake area of the engine, but which one? If so it's a 10 min job to swap with a new one and I won't need to risk being financially taken advantage of with such an easy repair. Is this a common issue with this model? Can anyone offer some advice, please?

Edited May 8, 2023 by Hiro
Personal contact details removed

[Hiro]

Toyota are correct, your engine (7AFE) has a MAP (Manifold Absolute Pressure, aka vacuum) sensor, not a MAF (Mass Air Flow) or AFM (Air Flow Meter) sensor.  The MAP sensor will be a small black box most likely bolted to the firewall, and connected to the intake plenum via a vacuum hose.  It is also most likely not the problem.

 

Engines need 3 basic things to run - fuel, air, and ignition (known as the fire triangle).  If the delivery (or the timing) of any of these is impacted, then the engine won't run properly (or at all).

 

Air is the easiest to check, and is also the one least likely to cause problems - basically, unless the air filter is completely blocked, or the throttle is stuck closed and the idle passages gummed up (or conversely a significant vacuum leak after the throttle), then the engine will run fine.

 

Next is ignition.  Check the condition of your spark plugs, plug leads, distributor cap and rotor, and replace anything which is worn/cracked/broken.  If you can get the engine running, then bridge the TE1 and E1 pins on the engine diagnostics connector (under the black plastic cap attached to the passenger side strut tower) and use a timing light to check that the base timing is correct (should be about 10 degrees BTDC).  If not, then loosen the distributor and rotate it to set the correct base timing.  The condition of the spark plugs can also help diagnose if the problem lies in the third point of the triangle, fuel.

 

Lastly is fuel (the hardest one to check, and to fix).  If the engine fires but doesn't want to run, then it is almost certainly a fuel problem.  The fact that you can get it running briefly by spraying tonnes of MAF sensor cleaner (essentially pure hydrocarbons) in the intake, much like Start Ya *****, makes me think that the engine isn't getting enough fuel.  Pull out the back seat and see if you can hear the fuel pump priming when you first turn the ignition key to ON.  Whilst you're there, remove the fuel pump (this might need the tank dropped on the AE9x, can't remember) and see if the filter sock on the end is clogged.  Test the fuel pressure at the fuel rail.  Get the injectors cleaned.  Replace the fuel filter (in the engine bay).

 

Your biggest problem is that it is intermittent, and thus you can't tell straight away if the component you replaced/cleaned etc has actually fixed the problem until the problem goes away permanently.