1990 Southwind motorhome won't keep running

[april10]

we have a 454 Chev engine, with TBI. It will start, but cut out and die within 1 min. maximun. We've sprayed starting fluid into the intake (TBI) and it died anyway (it made no difference). We also pushed in on the EGR valve when it was running in case it was stuck somehow, but that didn't solve the problem. It will restart immediately after dying. I've inquired about this problem before, but we have'nt found what's wrong yet. Would appreciate more advice, if possible. Thanks!

[ac_bill1]

Argosy24 wrote:

TBI (throttle body injection) doesn't have a carb it has a throttle body. A throttle body doesn't have an accelerator pump which gives the shot of gas when moving the throttle linkage.

That's true, it is a TB not a carb. The earlier Chev TB certainly looks like a carb, and not everybody knows exactly what a TB is, so I used that term for the sake of simplification..:)

My TBI will still squirt fuel with the engine off, must be residual pressure in the lines..

[wildmanbaker]

Also check the outside shower to make sure the hot and cold water valves are turned off. Good work on finding the alt and battery problem.

[2bzy2c]

Hot water bypass valve not turned off. Check the fittings near the water heater.

[april10]

We figured out we had a bad alternator and battery. It starts and runs great now. Now we have another problem to solve: there was a leak in the hot water tank area before we bought it, the previous owner fixed it. The electronic pilot works, burner works, tank doesn't leak, but when we turn on the hot faucets, it runs cold, then lukewarm for about 5 secs, then run cold continuously. Any ideas?

[wildmanbaker]

Larry probably has it right. There is a minimum voltage at which the ignition will quit working. Battery could be bad, but the alternator should provide voltage to keep it running. Most TBIs will give a small spray of fuel, when the key is first turned on, to help starting. We need to wait for the OP to get back with what they have found out, before we do any more guessing.

[Daveinet]

Some how I missed the post about the battery/alternator. Thanks restating it.

[2bzy2c]

april10 wrote:
Battery appeared to be dead and charger would not charge it. Then I jumped it with my pickup truck, and engine started and continued to run with jumper cables connected. Checked voltage at 13.90 volts, then disconnected jumper cables and voltage started dropping withing about 2 mins down to 8 volts, and engine died. Battery slowly recovered to 11 1/2 volts. Then I put battery back on charger and it read 13 volts, set at 2A charge. Started engine, voltage dropped to approx 8 volts and engine started to die, switched charger to 8 amps, and engine recovered and continued to run. Any ideas on what to do from here?

If you tried starter fluid and that did not help, then the problem is not fuel related.

Look towards your charging system. Based on your observations, you do not have enough voltage to keep the engine running. Alternator would be my guess. Sad thing is, when the alternator goes bad, it drains the battery and more often than not, the battery is bad too.

Take the alternator off and have it tested ay most any auto parts
store.

Best of luck, and please do check back and let us know the outcome. It benefits all of us.

[Emperor]

PS a fuel injected engine does not have an accelerator pump to shoot fuel with the engine off and the throttle is moved. Sorry

[Emperor]

If the coach runs with the jumpers on and trys to die when they are removed the answer is obvious. You are not supplying the coach with at least 10 volts to run on. What is causing that? More likely the alternator than the battery since it should run on the alternator after the engine starts. However the battery could be damaged due to the defective alternator. There is a simple test to check to see if there is anything draining the battery when all switches are off. Remove the positive cable and touch it to the positive battery post and see if there is a spark(it might be hard to see in bright light). There should be nothing that draws enough current as to make a spark. If there is one you may be able to locate the draw by removing fuses one at a time. I hope this helps you with your problem. Good luck.

[BrianinMichigan]

Bad ground wire from the chassis frame to the engine? Try taking a jumper cable from the engine to the frame. It's a cheap try. It fixed my PU truck when it wouldn't run

[Mike_M2]

MountainAir05 wrote:
Sounds like fuel. If memory serves me power is sent to the fuel pump for a 20 seconds or so, then after engine starts the oil pressure switch ensures you have power to fuel pump after you engine starts. You can check to see if your pump is working after startup. You can hook up a fuel pressure gage and see if pressure drops. Also a timing light will show spark.

I believe the pump stays on from seeing voltage from the alternator on this model.
Here's what is happening, when you turn the key on the pump automatically turns on for a few seconds to bring the fuel system up to pressure. This is your initial start.
After start, the alternator current flips the pump relay and keeps the pressure up. This is what is not happening and is probably caused from a problem with the pump shutoff system. You can jump the relay temporarily and the motor will run. They set it up like this so that if for some reason the motor stops the pump won't continuously run.
When you had it jumped from another truck it saw voltage from that alternator keeping it on...

[Daveinet]

Argosy24 wrote:

ac bill wrote:

Even with the TBI engine not running, you should be able to look down inside the carb, (air cleaner off) and when moving the throttle lever on the side, still see gas squirting down into the carb.

TBI (throttle body injection) doesn't have a carb it has a throttle body. A throttle body doesn't have an accelerator pump which gives the shot of gas when moving the throttle linkage.

That is all irrelevant because he stated that he sprayed starting fluid down the intake and it still stalled, so there is not a fuel delivery problem. The problem is electrical.

I'm also not sure how we got off on to the alternator/battery tangent. If there is enough battery to turn the engine over and start, there is enough battery to keep it running. When the battery goes dead, the first thing dies is the fuel pump. The engine will spit as it leans out, and eventually die. This takes quite a while before the battery will be dead enough to not have enough pressure for the computer to compensate. This is all gradual process. Once it is too dead to run the fuel pump, there is no way it will come remotely close to cranking over. Alternator failure was a common problem in my old Pontiac Transport, so I became very familiar with the symptoms as one tries to limp home and not quite make it. If it starts and runs, and then just dies, its not the battery or alternator. Since he did not mention a check engine light, my guess would be the ignition coil.

[Argosy24]

ac bill wrote:

Even with the TBI engine not running, you should be able to look down inside the carb, (air cleaner off) and when moving the throttle lever on the side, still see gas squirting down into the carb.

TBI (throttle body injection) doesn't have a carb it has a throttle body. A throttle body doesn't have an accelerator pump which gives the shot of gas when moving the throttle linkage.

[Captain_Happy]

I could be wrong, I have been before. But after reading your last post, it sounds like your main battery is dead, and the alternator isn't putting out any voltage.