Mechanics

COULD THE FUEL PUMP BE BAD AGAIN?

1992 Dodge Shadow • 4 cylinder FWD Manual • 224,834 miles

Hi Everyone and Happy Holidays,
Earlier, I sent an Email on some tests that we ran on the ignition circuit of our 1992 Dodge Shadow. Like I said in the other Email, the car left us on the side of the road the other night.
This is what is going on:
The problem is that the other evening; after being parked at a store for a few minutes, the car wouldn’t start back up – all of this was sudden and without warning. The next day; we took the air cleaner off, and while watching the injector operate (as the car was trying to run) – it was spraying erratically, splashing fuel, etc. Thinking the problem was fuel related and since we had already replaced the fuel pump earlier this year – we replaced the one fuel injector and pressure regulator in the throttle body. Now the fuel being sprayed is a lot smoother, straighter, and more controlled – but the car still runs the same – terrible.
Basically, the car will not start unless the gas pedal is pressed. When the car does start it runs extremely ruff and keeps trying to die. Next, we did some checks on the ignition system – which led to the earlier Email (that Email is in the electrical section of this site).
A little while ago; we hooked up a fuel pressure gauge and while the car was trying to run – the fuel pressure held at about 40 psi, but as the car died or was turned off the gauge needle immediately fell to 0 psi. The fuel pressure was the same with and without the fuel filter installed.
I guess the most aggravating thing is that earlier this year we had to do a bit of work on the car. The last thing we done was replace the oil pump. Some who visit this site often, may remember; we posted questions about the oil light coming on after replacing the oil pump - but in the end; when we replaced the oil pressure sending unit the light went off and stayed off; so-far-so-good. But here’s the kicker; the fuel pump was one of the first things we replaced after it went out. And it has worked fine - in fact the car has been running fine for some time now.
Sense the fuel pump isn’t even a year old yet, is it possible that the pump is out again? And if the fuel pump has gone bad again and this quick – how is this possible? Like a lot of people on a tight budget, we got the fuel pump from AutoZone.
We also gathered some computer codes by using the key cycle method; the codes are: 12, 13, 15, and 55
Thanks for everything and again Happy Holidays to all
Avatar
Sunshine03
December 24, 2011.



The fuel pump sounds like it's fine.

It sounds like the idle air mixture needs to be adjusted. There should be a screw on the throttle plate to accomplish this.

Rivermikerat
Dec 25, 2011.
Hi
Sorry I didn’t add this in the first Email. Just wanted to add; the fuel pump can be heard as it runs (both inside the car and at the filler cap). After looking the throttle body over – I could only find one screw and it is on the throttle linkage, but it has some kind of cap on it. Before trying to get the cap off, I tried manually opening the throttle plate a tiny bit and holding it – but the engine kept running badly. As a matter of fact when the engine does run; it acts and sounds like a vehicle does when the ignition key is turned off - but the engine won’t turn off – dieseling. When this weather clears a little bit I will try to get the cap off of the screw so I can turn it. Also, there is a solenoid on the front of the throttle body - the Haynes book called it an Idle Speed Motor. Could something have happened to it? And is this motor adjustable?
Thanks

Tiny
Sunshine03
Dec 27, 2011.
Code 12: None listed 11 maybe? No crank reference signal during cranking.
Code 13: Slow or no change in MAP signal.
Code 15: No vehicle speed signal.
Code 55: Completion of fault code display.

As you can see, I looked up what the various codes mean. I think the code 13 is the key. The MAP sensor sends a signal to the computer that the computer uses to calculate injector pulse width.

You should also check ignition timing. It should be within 2 degrees of 12 degrees before top dead center.

Rivermikerat
Dec 28, 2011.
Hi again
After finding out that code 13 was the MAP system and just to see what would happen, I disconnected the old MAP sensor, and then started the car – and believe it or not the idle got better. So like most people we got a new MAP sensor thinking we have fixed the problem. After hooking up the new sensor and starting the car – there’s no change. I even tried disconnecting the new MAP and starting the car – now the idle stays bad, this is crazy, and the computer has set the codes 12, 14, and 55.
After reading in the Haynes book that a code 14 may have something to do with the wiring, and being unable to make much sense out of the wire diagrams in the book; we tore into as much of the wire harness as possible and everything looks ok. We also found that almost every sensor under the hood is (in one way or another) connected to each other and to the computer. There were just a few wires that branched off and went through the firewall.
A few other things we have done are: 1)Cleaning and gapping the sparkplugs.
2)Checking all hoses and their connections - they look ok.
3)The timing belt looks good, it’s tight, and the timing marks line up when you rotate the engine with a wrench.
4)The car is idling so bad that it is hard to tell where the timing marks are when using the timing light. After I get the wires bundled back up – I’ll try the timing light again.
This is just a thought, but could something be wrong with the computer. I have also heard that if the ignition switch or distributor goes bad strange things can happen to a car. I have to admit this problem has us stumped.
Thanks

Tiny
Sunshine03
Jan 2, 2012.
Yes, it could be an issue with the computer or the distributor, or both. Does the Haynes book list voltages that should be present at certain locations? If so, do you have a meter you can use to check if those voltages are present?

Rivermikerat
Jan 2, 2012.