I just bought a 1985 Trans Am with a 305 TPI. It cranks but won't start. Checked spark at cylinder 1, have spark. Compression is about 135, just checked cylinder 1 so far. Spark plug is fouled. Fuel pressure is about 48 lbs with key on and cranking. Then fuel pressure drops slowly over the next few minutes. Im thinking an injector is stuck open. I found a set of 8 Bosch 19lb injectors on eBay for $47 new. Should I pull the trigger or do some more tests? Forgot to mention I took the regulator apart first and it looked fine and rubber was in good shape.

 

Pinch the return line and see if the pressure drop is the same. Imo, if the regulator gets opened, it gets a new diaphragm. Could be injectors, you can ohm them to determine if they're electrically ok. Does it pop a little with starter fluid? If not at all, might check timing as well.

Is it throwing any codes?

 

I am chasing the same problem in my 89. There are 3 things it can be - Fuel pressure regulator, stuck injector, or bad check valve at the fuel pump. If FPR is ok that eliminates one potential issue. Don't buy cheap Ebay injectors as others have had problems with them. Southbay Injectors seems to be the go-to for injector replacements for TPI.

 

I still lose fuel pressure with the return fuel line crimped. I tried pulling codes but the CEL doesn't light up at all, even when turning the key ON. Might have some dash light issues. I ohmed all the injectors, they all had between 15.5-16.9 ohms. I'm thinking I'll pull the distributor cap off and look at the rotor next. Might also make sure all the wires are in the correct position.

 

Well, if the return is blocked, and you're losing pressure, the fuel is going somewhere it's not supposed to. Might very well be leaky injectors. Or leaky cold start injector? You could pop em out and verify.

 

I didn't even know about the cold start injector. I will check that out tomorrow. After cranking for a few seconds I can smell fuel. Engine kind of tries to start a couple times and then seems to flood itself out. Ordered new spark plugs and FPR from rockauto today

 

Don’t buy cheap injectors you get what you pay for.
southbay fuel injectors can hook you up.

 

Cold start injector has 4.0 ohms. Fixed the wiring harness to the fuel pump relay. Replaced the relay. Still won't start. Waiting for my noid light kit from eBay. I'm not getting any dash lights when I turn the key ON. What's the best way to test the ECM? The 5 and 3 ohm fuses do not have power with key ON. I assume one of these is ECM. But the white letters are all worn off the fuse box

 

Ecm fuse is next to battery, check your fusable links at the starter if no power at the fuse box.
ecm
has accessory power and keep alive from battery. Look at 1226870 schematic

 

https://www.eecis.udel.edu/~davis/z2...ody-wiring.pdf

 

ECM fuse is good, 12 v each side. Relay is getting power and ground in/out. I started checking ECM pinout with my power probe. I have all the necessary power and grounds with one exception. The Burn Off Relay Control has 0v and it's supposed to have 12V with key ON. I see that it's up under the dash pad above where I pulled the ECM from. Maybe this Relay box needs to be replaced. I'll have to get to it and check the wiring. Also realized my keys don't have a resistor in them. The car still runs the fuel pump and cranks but obviously won't start. Ignition looks old, so maybe I simply need to buy some resistors and try to find the correct one to wire into VATS, although I have not located that orange wire yet.

 

You don’t have vats

 

Good to know. What are your thoughts on a bad Burn Off Control Relay causing a no start issue?

 

The car would still start without burnoff or without maf if tps signal is good.
i honestly wouldn’t try to start without basics spark and injector pulse verification.
a new fuel pump and good quality injectors cheap parts you will have issues .
get what you pay for

 

I read a thread on a Corvette forum where it said the engine would not start with a bad Burn Off Control Relay on an 85 because they are different from the later models. Not sure what to believe at this point. Previous owner replaced fuel pump. He cut a damn access door. At least I can test the wiring easily. That all looks good. I'll wait for my noid lights and new FPR before making any other decisions, but might have to update the car to 86-89 ECM and relays.

https://www.digitalcorvettes.com/threads/burn-off-mod-fix-for-85.26380/

 

I had a 85 with a bad maf, would start so who knows. The 870 to 165 ecm
is a good swap .

 

I went thru all the wires on the ECM and found one irregularity according to the diagram. The Park/neutral safety switch is supposed to have 12v with key on, and I have a ground instead. I pulled the center console apart to look at the switch. The yellow wire on top is grounded when in park or neutral. Purple wire under yellow wire is constant ground. Found pink/black wire that runs to ECM and it had ground so I gave it power with the power probe and cranked. Still won't start. Used a noid light and confirmed injectors are getting power and ground but the light was kind of weak. Had a battery charger going at 2 amps. I still don't have any dash lights when I turn the key on and can't pull any check engine codes. I think that has something to do with the no start issue. Maybe the ECM is dead?

 

If you're losing fuel pressure with the return line crimped, where is the fuel going?

 

Leaky injector I assume. No leaks from fuel lines. I would think the car would still start with a leaky injector. Probably run shitty but still run

 

I am going to upgrade to a 165 ECM. I know I need 2 relays with pigtails, ECM and PROM. Who can I go to for PROM programming? Im grabbing a Lisle repin tool as well. Anything else I might need? Found an old website with some good info, just want to cover my bases. Thanks

https://www.eecis.udel.edu/~davis/z28/ecm_swap/

 

https://www.ebay.com/itm/19495869663...mis&media=COPY

Few people here that do tpi programming

 

https://tpiparts.net/inc/searchresul...Relay&n=638430

 

I have a parts harness or can snip pigtails off a 86-87 harness for parts only but maf burnoff pigtail is junk

 

believe you also need a analog maf the digital one might not work with the 165

 

https://www.ebay.com/itm/14449449134...mis&media=COPY

 

Replaced the ECM and relays to the 88-89 style and got the car running. Seemed to run well, maybe idles a bit high.

 

Mine did that too the first time I got it full of coolant and pressurized. Did the oil turn into milkshake, or is there oil in the coolant now? If it all looks good, let it cool down, suck up all the fluid it wants, then check the coolant in the rad and the overflow again and try again. A lot of my very early symptoms stopped reproducing after the engine had a few heat cycles. Just monitor it really closely and do several short test drives.

 

I’d fix the overheating or air bubble that burped first. If still 1226870 a Vette prom
will work for the swap iirc hlh3200 are the letters for it .

 

Removed the thermostat, changed the oil (no milkshake in oil or coolant) topped off radiator and let it run with the cap off for a while

 

Before the radiator cap was put on was it ran until t stat opened and topped off ?

 

Hmm, how hot is it getting when it boils like that?

 

I had another "Doh!" Moment with this car. The fans were simply not turning on. I didn't have the relay wired correctly. I'll fix that tomorrow and report back. Can't believe it took me this long to figure it out

 

Turns out the wiring was good, relay is working, but the fan doesn't turn on. Used a power probe to check power/ground and it's getting there but fan motor is burnt out. Trying to find a new fan now

 

You should be able to replace just the motor part.

 

Couldn't get the nut off the fan to remove the fan from the motor. Even with an impact and holding the fan it just spins the motor behind the fan so the nut wont come loose. Does anyone know of another fan from a more common car that would fit in my Trans Am? Would be nice to run to the junkyard and grab a fan. I can re wire the fan as long as it physically fits behind the radiator without hitting any pulleys or the air box/tube.