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Discussion Starter · #1 ·
I finally got the impala back on the road. Still fine tuning and getting everything back to working order. Something happened yesterday, and I am striking out on what the potential cause could be.

I was driving on the interstate at 5:30pm (traffic), so it was stop and go. Car was driving normal. I was driving forward at idle; I applied the brakes; and after I came to a complete stop, the rpm's dropped sharply, the car died and would not restart.

I pushed the car to the side of the road, and checked everything. All fluids were/are good, coolant temperature was good (150-160 degrees), gas was getting to the engine (checked schrader valve port with car on/engine off), intake was clear and clean, all sensors were plugged in, no check engine light, grounds looked solid, spark plug wires were checked at plugs and opti, no fluid leaks anywhere, and the battery/starter were strong and tried to turn the engine over. I let the car sit for 10 minutes and tried to restart...nothing. The starter would engage, but the engine would not turn over.

I called a tow truck, and while I was waiting I continued to check things and tried to restart, but no success. After the car was dropped off in the driveway, I tried one more time to turn it over, and the SOB started up like nothing was wrong. I didn't change or check anything. I let it idle for 10 minutes with an occasional rev. No issues. Turned it off and restarted with no issues.

At this point, I don't know where to start looking for potential problems, and I am looking to see if anyone here can help diagnose/troubleshoot my car issue(s). Anyone with a similar circumstance?

Car mods: 357 ci by Golen Engines, LT1 aluminum heads with larger valves and bowl porting, Cam Duration 224,230 Lift .574,.569, 1.6 RR, rebuilt/upgraded 4L60E, 2800 stall converter by Edge, 30 lb/hr flow matched injectors Bosch, CAI by Clear Image, F-body MAF, try-y headers and cat back exhaust by Clear Image, electric water pump, 160 thermostat, deleted Cats, EGR and Air Pump, and PCMforless tune for all of the above. Everything else is stock. No forced induction.

I should note that I was having idle problems caused by a faulty TPS. I replaced the TPS and reset it to read 0.70 volts (0.68 ideal). After I replaced the TPS, I also reset the IAC. The engine appeared to idle perfect after these corrections were made. I even made another 30 mile trip with a lot of stop and go prior to this stall incident, and I had no issues.

Thanks in advance.
 

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When you say the engine wouldn't turn over, it wouldn't actually turn over like it was siezed or just wouldn't fire?

Did you check spark right there while everything was still hot?
 

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Discussion Starter · #3 ·
Engine would turn over, but would not fire. It did not feel/sound like the engine was seized or seizing up.

I checked the spark plugs as soon as I got the car on the shoulder while everything was hot.
 

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check your fuel pressure with a gauge, classic fuel pump symptoms.
you can press open the schrader valve on a empty gas tank and you'll get gas out.
 

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check your fuel pressure with a gauge, classic fuel pump symptoms.
you can press open the schrader valve on a empty gas tank and you'll get gas out.
X2 seen it/experienced it multiple times. Most likely a burned connection on the in-tank wiring harness. They work when things are cool, but when stuff starts to heat up the connections drop out and it shuts down. When things cool off or get jostled around (IE loading on tow truck) and it goes back to working. Check fuel pressure with a gauge (should be at least 40ish with key on engine off). If it dies on you again, you can sometimes get them going by rapidly banging on the bottom of the gas tank in the center. I've gotten a few going this way. At least good enough to get home...
 

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Discussion Starter · #6 ·
Ok, thanks guys. I will start there and report back my fuel pressure.

I replaced the fuel pump with an Airtex about a month ago. When I did this, I also cleaned the electrical connections, but I ended up reusing the spade connectors. If I have solid fuel pressure, then I might drop the tank and solder all the connections to remove that as a potential failure. I may even replace the sending unit with a new ACDelco since the new unit appears to have fixed a lot of the known issues with the original.

Thanks again.
 

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You may want to consider a different fuel pump anyway. I haven't been all that impressed with Airtex pumps. They seem to be a lot louder than the Delcos. I had a dead one right out of the box too. I wouldn't have even bought it, but I knew I'd be scrapping the car in less than a year. Check Rock Auto on the Delco pumps, they were $80-90 the last time I bought one. Not much more than the airtex.
 

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Discussion Starter · #10 ·
Let me see what I can do. Amazon has both the fuel pump ($67) and the sender ($201). Plus free 2-day shipping with my Prime account. Not bad prices, but still a chunk of money. I will pressure test, sleep on it, and decide.
 

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Discussion Starter · #13 ·
Tested the fuel pump.

Ignition on/Engine off: 42 psi (dropped about 5 psi over a couple minutes)
Engine on: 42 psi (idle), 38 psi (up to 3,000 rpm)

No trouble starting, idling or reving. Sounded great.

The readings sound a little low, but not low enough to be the direct culprit for causing the car to stall and not restart. Something like the wiring could be at fault. I at least agree that taking a look at the wiring harness and terminals on the sending unit/pump to see if there could be a potential corrosion or varnishing issue.

Like I said, the fuel pump is new, and I cleaned all the terminals prior to reinstalling. The spade connectors are not the most reliable.

Between the heat and vibration, does anyone think the pump or wiring is still a potential cause?
 

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Those numbers sound pretty normal, but you may have to wait until it fails again to diagnose it. Check the pressure when it stalls next time.

Also, have you tried the wiggle test while it's running (wiggling all the various wires under the hood)? I found a break in an ICM wiring once this way that was causing intermittent stall problems.
 

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Those numbers sound pretty normal, but you may have to wait until it fails again to diagnose it. Check the pressure when it stalls next time.

Also, have you tried the wiggle test while it's running (wiggling all the various wires under the hood)? I found a break in an ICM wiring once this way that was causing intermittent stall problems.
I can't count how many times I've been bit by those grounds right by the ICM too.
 

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Discussion Starter · #16 ·
When I was on the side of the road, I did the "wiggle test" on the connectors and grounds to make sure all terminals were snug and I didn't have any loose grounds.

Grounds I checked: LH & RH frame grounds at front of car, grounds next to ICM, LH rear block ground, RH front of block where negative battery cable connects, negative battery cable fender ground, and the additional frame ground that comes on my Innovative Wiring battery cables.

When I re-installed everything on the car, I wire brushed every ground terminal and coated with dielectric grease before torquing down.

I painted the frame and engine compartment. Before installing the harness and grounds, I scuffed all ground surfaces up, but I might go back over these and make sure I have exposed bare metal where I painted.
 

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your problem most likely is an electrical short some where. since the wiring was messed with check that all the wiring has LOOM covering the small wires. remove the PCM check all the wiring connectors for damage chaffing on the metal frame/inner fenders..

could be the fuel pump did shut down , then after the tow job vibs it started to work again but some wire shorting can do the same thing.

I would keep the fuel gauge and a volt meter on you at all times so when it fails again your ready ....

with no codes again some wiring problem..
 

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Discussion Starter · #18 ·
J cat - Will do.

Alternate idea: Could it be the ECU itself trying to learn how to control the car. I literally took the entire car a part and put it back together. The car was almost completely stock prior to this project. Now it is extensively modified. Nothing over the top, but it is not stock.

I finally got the car running about 3 weeks ago. I took the car on a handful of short (< 3 mile) trips and just two longer trips, so there really hasn't been much time for the computer to learn all the new changes that I forced on it.

I will check the wiring, but does anyone think the situation I described above is plausible.

Thanks.
 

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By checking spark, you pulled a plug wire off and observed spark while cranking?

If that is the case, you have a fuel pump electrical issue. Open the trunk, on the left side is the fuel pump ground on the trunk hinge support. Clean, seal and retighten this connection. Then drop the fuel tank and fix the wirng harness bulkhead connector. thats were your issue is. I personally would install an upgraded fuel pump harness from racetronix or one of Garys hot wire kits.

Chris
 

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Discussion Starter · #20 ·
Rocko, yesterday when I checked the pressure, I also confirmed spark in plugs 1 and 4 as you described.

I contacted Gary. He said that he has made one, but does not currently offer a fuel pump harness. He did suggest the same root problem with the fuel pump ground on the trunk hinge. I checked and it was tight an corrosion free. I will add this to the list of things to clean. I will also expose bare metal, replace the self tapping screw with a standard nut/bolt, and apply dieletric grease. I will also check for a short in the line.
 
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