crank but no start
Thread Starter
Cruising
Joined: Jun 2009
Posts: 13
Likes: 0
crank but no start
I just finished rebuilding an 86, and i got a reading of 8.2 KOhms for the resistence in the plug wires. If im correct, shouldnt they be like 0.2 ohms???? I replaced the plugs but not wires and the distributor cap but not the rotor, what are the chances that the parts i ddnt replace are the case?? Theres only 86K miles on the motor. any suggestions??? Thanks
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Plug wires should measure about 5000 ohms per foot as they have a carbon center to stop ignition interference. Use your timing light during cranking to see if you have spark and spark at the right time. Measure the fuel pressure, should be 35-42 psi and it should hold up for a long time after the ign is off. Use a noid light (parts house) or make one with an LED and a series 680 ohm resistor across an unplugged injector cable during cranking to see if the injectors are being pulsed. If you make a test light, the anode of the LED goes to the injector wire with 12v on it all the time. Spray starting fluid into the Mass flow sensor and see if it will start, if so, no fuel is being injected. If all is ok, then run a compression test.
Thread Starter
Cruising
Joined: Jun 2009
Posts: 13
Likes: 0
ok, it cranked before i rebuilt it. I didnt touch the timing or anything like that. I think im getting too much resistence in the wires. I got fuel pressure, how likely would the distributor contacts? I do not have a timing light though, but should i be getting 12v to the connector from, the battery to the distributor???
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
The resistance you measured is normal and will not prevent a spark. It doesn't matter what you did or did not do, buy a timing light, a fuel pressure gauge, a noid light (or make your own),a cyclinder compression gauge and become a real mechanic! You do these tests to find out what is preventing the engine from starting, NEVER assume that any part of the engine is perfectly ok and doesn't need to be tested. If you do, you will never find out why your engine won't start. ALWAYS be suspicious of everything. Yes, the plug going to the distributor has one wire with 12 v on it and yes, it is possible that the rotor is defective and preventing a spark at the plugs. Cranking the engine with no plug wires connected can cause arcing through the hemispherical dimple at the center of the rotor insulation and this makes a carbon track and then that is the only place the spark occurs. Look closely at your rotor.
