HELP! 305 TBI intermitant no spark

i went to start my 715 after going to the store and it wouldnt start. there is no spark, and no check engine light. it just cranks and cranks and cranks. after letting it sit for a bit it will decide to start, but will die when i hit the gas. eventually it will start and not have any problems at all. it only has problems when trying to start it. both fuel pumps are good and the filter is clean.

i took the distributer cap off and its really rusty in there. the cap and rotor are somewhat corroded and the little 8 pronged pick up wheel in there is really rusty. is anyone familiar with any sort of problems like this with 305 TBI engines? i was thinking it could be the HEI module, but lack the tools/knowledge to test it. could the whole distributer be the problem? if i need a new cap, rotor, and HEI module should i just get whole distributer from the junkyard? i need to drive the 2400 miles home to NH on Saturday. any help would be greatly appreciated. thanks.

-BrianM

if it is an early production engine wiggle the dist shaft and check for slop. early dists. were prone to bushing wear and develop a wobble that causes the star wheel to contact the teeth on the pickup coil. You may have to spin the engine to see the death wobble. also, these are prone to burning a tiny hole in underside of rotor that is hard to see. it is caused by voltage going to path of least resistance rather than through bad wires.

did you check for power at the coil? does it flash when you try to start it? does the check engine light come on when it finally starts to run? fuses and grounds all good to ecm? do you still have the aldl connector. jump across it and see if it flashes codes. if it flashes but has no codes stored, go and check for fuel pressure if ok should be around 15 psi, with a test light undo 1 injector harness connector and jump across the 2 terminals with a test light and crank it, if it flashes then check for fuel on the other injector while cranking over. if none you probably have bad injectors change the regulator at the same time if needed, but if no signal to injectors it leads back to module problems and probably a bad pickup coil. you can ohm test the pickup coil, dont remember the exact ohms now but with the rust Id guess its a shot dist and your best bet would be to replace the whole thing if it rusted up and ask about the replacement. how many miles on the engine and have them or pull of the cap your self to see if its the same way too.
your dist. sends a signal to ecm and ecm fires the injectors. the dist fires the coil and the ecm sets timing according to the info in prom. probably either lost you or cornfused the beans out of you? hope this helps. hopefully dave a helped and you dont need to go this far.

i dont have a fuel pressure guage but im pretty sure fuel pressure is good, becuase it does the same thing on both tanks and when it does run it runs pretty good. i checked the distributer wobble and it is pretty tight- no play at all. i have mitchel on demand and so i was able to pull up the wiring diagrams. i checked all the ground wires and such on the computer. all check out good, and the engine block is also grounded out properly. i checked for spark when it does not want to start and there is none. there is also no fuel coming from the injectors. i would imagine that is because there is no spark. my ohm meter is really messed up at the moment and does not want to work right so checking resisance may be difficult... i think the batteries may be low, i'll try that first i guess. i am starting to lean toward replacing the entire assembly. is there important electronics in the distibuter itself or is it all in the HEI module? if it runs good part of the time would that indicate a good distributer itself? thanks for the help.

-Brian M

it would be a lot cheeper to get a good used one. the only thing that isnt repairable is the wear in the dist housing. the dist is disassembled then you remove the old pickup coil and install a new module. take the role pin out at the drive gear, spray some w-d down the shaft and spin it back and forth until the shaft comes out. take a wire wheel and clean the shaft off and clean the contact area of the module off and the bolts themselves and reasemble. remember to mark where everything was before you took the dist. out. you can try to replace the module first and dont have to remove the distributor, just remove the cap, the 2 module screws disconnect the pickup leads and replace it.all of the electronics are in the module itself, it picks up a signal from the pickup and send a signal to the coil to fire and at the same time it sends the signal to ecm to fire the injectors. glad to be of help if any.

When you crank it with the air filter off, you should see pulses of fuel being sprayed in. The ECM will fire the injectors during crank mode to "prime" the motor. IIRC, it should do this even without a spark trigger. If it runs good when it finall actually starts, that tells me that your dist. is OK. Maybe something isn't getting the crank signal. The ECM runs in CRANK mode when your're trying to start the motor. If it's not it crank mode, but you ARE cranking, that could be the issue. Some some more ideas for you to look at. Good luck.

hmm... sounds good. thats a lot of help. thanks.

-Brian M

i replaced the HEI Module, distibuter cap, and rotor. so far so good. no problems. thanks for all your help. i shoudl be good to go for the trip

-BrianM

we are just glad we could be of help you get back on the road and hope to see you at the fe!