Car cranks but no start. Fuel injectors not releasing gas

Quote:

---

Originally Posted by Shiftingshaddow

Would the fuel pump, if already weak, just not be able to give enough pressure if it hadnt been used in over a week? The car has 190K on it.

There wouldn't be any kind of sensor, that if bad, would cause no power to the injectors?

Tomorrow can try more to see if they are getting pulse and check the fuel pressure with a gauge but for now have to ask questions in hypotheticals.
Thanks guys.

---

You are on the right track here. No sensor will stop the injectors from opening during the prime sequence for startup. This is exactly why you need to verify that the injectors are getting a +12 volt continuous when the key is turned to the on position. The +12 volts are looped from one injector to the other; all the same circuit. Just test one and that's it. This takes about 1 minute to perform.

Next is the fuel pressure...should be > 45psi at the rail when the pump primes. The pressure may bleed down a bit after the pump shuts off. Don't try to start the car and watch the fuel pressure after the key has been turned to the on position. It might lose 10 psi over 10 minutes which is fine.

Here is what you need at the injectors for the car to start:
1) Fuel rail primed
2) Fuel pressure >45 psi
3) +12 volts continuous with key on
4) Commanded ground from the PCM

If you have all of this and it doesn't start then the injectors are bad or clogged. You've already verified that it will run with fuel so all other systems are operating properly.

"Like I said earlier, make sure the ground wires for the injectors are continuous with chassis ground. The grounds are looped from one injector to the other"

What do you mean continous with chassis ground? Would you happen to know where this ground is supposed to go? Is it tied directly to the injectors' circuit?

I remember there being several "grounds" dangling near the starter that I wasn't sure where they went. Bro hooked them up and I'm not sure he knew where they were supposed to go. I didn't unhook those so I don't know where they were supposed to go either. Could this be one of them?

you have the battery and 2 other O ring grounds that bolt to the trans bell housing bolt. the one that has a stud on the end of it. they bolt in right above the starter, and yes if one was left off it could keep the car from running.

make sure the starter is also wired correctly.

Thanks guys for your help. Your suggestions helped us trace the line.

What wound up being the problem was a miswire. There is a sensor coming out of the block that I'm not sure what does.....the throttle position sensor and this sensor's plugs were switched around. Checked fuel pressure and it was fine. Checked voltage at all injectors and they were fine. Went down the line and found that the throttle position sensor was not getting power. Turns out those two plugs are the same plug. Switched them around and viola. Runs awesome. Never would have noticed had we not starting checking voltage. Thanks again guys. Physical moving parts are easy to figure out but how systems work with electricity is a whole different animal. I learned a lot doing this.

I never would have guessed that in a million years.
Your gonna have to be more careful next time with the wiring.

that's the maf and tps. Which...should be keyed and not possible to mix up. Cool though.

Scotty...next time toss that ground to the trans out sooner. I was 99% sure it was that.
Rico.. pcm pulses ground, not power.

Oops, got it backwards.
Thanks Bill

I'll edit my posts for the next guy.

Easy way to remember it is that in most casese the circuitry of the pcm can't handle power or high power. Therefore it does as much with grounds as possible.

Makes sense. Ground returns are always low power.

I edited the previous posts as to not confuse the next poor guy having a similar problem.

No, it wasn't the MAF. It was coming out of the block below the valve cover if I remember correctly. If you are looking at the front of the car it is driver's side on the front side of the engine facing you. They were the same three pin connector--that is why they were easy to mix up. Seeing as to how the TPS wasn't getting power and looking at the path of the cable plugged into it was obvious that there was no way for power to get to it. But it wouldn't have been spotted had voltage check had not been done.

I am the type that will mark the wires and vaccums or take pictures of them or at least get a diagram. My bro just likes to go fast on the tear down and then figure them out on the assembly. He thought they would all be different--that is why he wasn't too concerned with it.

Er uh..the coolant sensor then,. I'll have to take a closer look. I didn't think they'd interchange either.

Heres one, battery went dead in my 07 gp 3.8l base. Put new battery in it, cranks but wont start. Hooked up code scanner, comes up with 10 dtcs. 2 o2 circuits, evap cir, and all 6 injection circuits. Any possible ideas. Im thinking something simple. Of coarse im being optimistic.

Quote:

---

Originally Posted by stef101

Heres one, battery went dead in my 07 gp 3.8l base. Put new battery in it, cranks but wont start. Hooked up code scanner, comes up with 10 dtcs. 2 o2 circuits, evap cir, and all 6 injection circuits. Any possible ideas. Im thinking something simple. Of coarse im being optimistic.

---

post the codes.

one may have something to with the others, cant tell by just you saying 10 dtcs.

and with 10 codes you should just start your own thread for your problem. keeps confusion down.

Here they are, P0030-Ho2s.heater control cir bank 1sensor 1,P0036-Ho2s heater control cir bank1 sensor2, P0201-P0206-Injector cir open, P0443- EVAP emission sys purge control valve cir. With key in run position there is no power to 5 possibly 6 fuses, They are #12-emissions, #14-o2ssr, #17-ETC,#20-fuel inj, #24elek ign. Checked all relays and they all click. Dont think i have power to the 1a diode fuse either. Checked fusible link at the starter and that checks out fine. Now this is a 07 gp 3.8l that sat for a week or 2 and the battery died out. Tried to jump start and wouldnt fire. Put a new battery in it because the old one was bad. Any thoughts?

You said you checked fuses, because that sure sounds like one of the supply fuses popped.

Yes, all the fuses and the battery mains were taken out one by one checked with a continuity tester and reinstalled. The fuses I described earlier have no power to them at the fuse block. Now im just your regular weekend mechanic but ive came up with two possibilities. 1,fusible link somewhere else besides at the starter, 2, the theft deterent system. If theres no power at these fuses than there would be no reason to check for power at all these individual points. Any other possibilies or input would be great

Give us a little more background. This a daily driver and the battery went dead, so it was pulled and swapped all in one shot? No other things were undone?

If you have no power to those fuses with the key on, then it's a trace back from there. What feeds the power to those fuses. I assume they are in the under hood relay/fuse center?

The car sat for about a week in the drive. Wouldnt start, all the starter did is click rapidly. Tried to jump it, had to let it sit there a little, cranked pretty good but still wouldnt fire. Tooked the battery out got it tested at 2 places, both said it was bad, got a new one installed it cranks great, wont fire. Checked all the fuses one by one visually and with a continuity tester, all came out good. Turned the key in the on position and started to check for power at all the mains and fuses. All have power to them except, #12-emission,14-o2ssr,17-ETC,20-fuel inj,&24-elek ign. I drove the car prior and noticed it did turn over slowly at first but did fire. got the oil changed and ran a few other errands, put 87 miles on it, started great, ran great, no light on the dash. Parked it and here we are. I did inspect the wiring harness for rodent damage and none is visible

You need to trace back the supply to those fuses that you don't see power at. With key on..injectors, o2 sensor etc should have power.

I experienced this myself and wanted to share for those who face the same problem.

I had 12+ to each fuel injector. PCM would not pulse fuel injectors while cranking. If you start the vehicle off ether then the injectors would fire and car would drive.

It ended up being I had a 1 bar MAP instead of a 2 bar MAP installed (GTP top swap on 04). The PCM not reading the correct information from the vehicle sensors, did not spray fuel while cranking but did while running.

So if you have a no fuel injector pulse while cranking issue I would look into the sensors and make sure they are reading correctly, plugged in, etc. Hook up a scan tool and read the live data. Mine never threw a MAP code.