1993, 240 - Fuel Relay Proper Operation
 

Hello All! I am troubleshooting a no-start on my '93 240 wagon -- wondering if anyone could take a look at their relay and confirm that my ECU/EZK is properly switching both relays. to see the video I've uploaded of my relay in action at start. Thank you in advance!

a video won't tell us the relay is properly functioning.

connect a test light or volt meter to the tank pump fuse (and ground), when you turn on the car, you should see voltage there for a second or so then off. crank the car, and you should see voltage again until about 1 second after the car stops cranking.

if you do this, and see that, then your fuel system relay is properly working.

Thanks pierce! Test light confirms the relay is working.

As a side effect, the fact that the fuel pump relay comes back on when the engine is cranked tells us that the crank position sensor is working...

so... I think my next step would be to crank it for 15 seconds or so, wait 15, crank another 15, then pull all 4 spark plugs reasonably quickly, see if they smell like gas and/or are wet.. if so, then the odds are pretty good the fuel is being pumped and the injectors are firing.

I'd also take one of the plugs, put it back on the spark plug wire, and use some insulated pliers to hold the side of the plug against a engine block ground, and have someone crank, verify you see a fat strong blue spark... no spark, its time to start troubleshooting the ignition system...

ignition troubleshooting, I'd start by verifying there's power on the '15' pin of the coil when you turn on the ignition. no power, its time to check the ignition switch. if there is power, I'd use a test light on the '1' pin, and have someone crank, verify the '1' pin blinks when the engine is being cranked... no blinks, its time to check the ignition 'power module'.

note, I do NOT recommend randomly replacing parts, there's a lot of crap out there in the parts market for older cars now, and odds are 50-50 that you'd get broken 'new' parts, especially if you buy on price and shotgun replace a whole bunch of stuff. if you determine a part is faulty via diagnostics, then when you replace it you can do the same diagnostic test to verify the replacement is good/bad, and or you have to look deeper.

Pierce - thanks for all the added info! Good to know how to at least start to rule out ignition system.

Some strange facts about the wagon's status. The motor has fired up and idled for about 10seconds before quitting (this rules out anything wrong with ignition, no?). This happened when I unplugged the AMM/MAF. However, with AMM plugged in I have gotten the engine to turn over but it quickly died. I am getting voltage to the AMM. Need to remove AMM and clean it to see what that does.

Also, noticed that even though fuel pump fuse has voltage on load side, the main pump under the car seems silent to me. Silent also at the tank when I put my ear to the sending unit.

Thanks for any other words of advice!

MAF cleaning has hardly ever done anything for me.

there's a easy way to test both fuel pumps independently on a 240 using a jumper wire... remove the tank pump fuse (I think its fuse 4?), and jumper the left side of the fuse holder to a source of 12V (like fuse 6), that powers just the main pump. jumper the right side of the tank fuse holder, and that powers just the tank pump. the main pump is pretty quiet, and hte tank pump is easiest to hear by removing the fuel cap and listening at the filler pipe, especially when the tank is below 1/3rd full.