Engine turns over, but won't start

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  #1  
Old 08-11-03, 06:54 AM
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Engine turns over, but won't start

We drove our 1990 Plymouth Grand Voyager (3.3l v-6, efi, overdrive automatic trans, about 150k miles) about 8 miles in 100-degree heat yesterday.It ran fine on the way to church, but about ten minutes later, when we were leaving, the engine would start but just barely idle, and would not respond to gas pedal input. Before borrowing the church van, I tried to start the Plymouth one more time, and it would not start. We were kind of in a hurry, so I didn't have time to check for codes or anything, but with the engine not running, I gave the fuel rail schrader valve a little stab with a key, and fuel sprayed out under pressure.
The van has been running okay for the last two months, since we came back from vacation (we drove the van to Missouri from New Mexico). On THAT trip, the van developed a habit of only responding to the gas pedal when it was almost all the way to the floor. It only did this when it had been running for a while, and when it was hot outside, or if it had sat for a little while after a short drive. I suspected the throttle position sensor, and someone on this forum suggested that was probably the case. I never replaced the sensor, though, since the problem seemed to go away once we got home. Could the TPS be giving me the problem I have now? Any help, as always, is greatly appreciated. Thanks - Chris
 
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  #2  
Old 08-11-03, 07:19 AM
Joe_F
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It could be. Check it with a digital voltmeter and tell us what you find versus the spec in autolibrary or your service manual.

As usual, back to "The Basics"----spark, adequate fuel pressure, air, timing, etc.
 
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Old 08-11-03, 06:20 PM
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Thanks, Joe. Once I get the van home tomorrow, after checking the basics, I will look at the TPS. As I do not have a timing light (it is on my shopping list, though), but DO have an inline spark checker that fits between the plug and wire, can I use this to check for spark on the distributorless ignition? Thanks again - Chris
 
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Old 08-11-03, 06:32 PM
Joe_F
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You could, but the shadetree method is to just pull a wire off, hold it to ground and have someone crank it over. If the spark is fat, blue and consistent, chances are you are OK.

Timing lights are a bit of things of the past...cars really don't have adjustable timing like they used to in years past.
 
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Old 08-11-03, 11:55 PM
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it could be a tps, however, i highly doubt it. the check engine light would have been on by now and the trans would be shifting horribly as the tps is also wired to your trans computer and is a major input for the shift points.

you SHOULD use your spark-checker inline of a spark plug wire as this DIS (distributor-'less' ignition system) will knock you on your tush if you get zapped--it is a strong ignition system. a timing light is useless on this engine(maybe to check for spark).

pushing the schrader valve is not the most accurate fuel pressure test, slightly low pressure will cause the problem you describe and can't be measured by how high it spurts out.

a slow or unresponsive oxygen sensor will definitely cause the one problem you described--engine wouldn't respond unless gas pedal is pushed all the way down---i've seen it many times.

first check for codes before unplugging anything(cycle key 3 times)

you can easily measure the tps voltage with a digital voltmeter as previously stated, just use a pin or small paper clip and backprobe the tps connector, one wire at a time with the key on, voltage should vary smoothly with throttle movement, and should also have 5 volts availabe and a good ground(the three wires)

while you have you dvom out, backprobe the oxygen sensor signal wire on the 2 volt scale. it should be switching quickly between .1 and .9 volts after the engine is warmed up. anything else and it's time for a new one, especially if it's stuck at .5


you might have two problems here, or just one causing the other problem, that's why an accurate diagnosis is essential. a digital voltmeter can be bought very cheap, like from the radio shack or sears or any place that specializes in electronic parts, much cheaper than a timing light. you only need a basic one to measure voltage and resistance.

let us know what you find out.
 
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Old 08-12-03, 05:28 PM
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Thanks for the info, guys! I got the van home this morning, and have since found the following: code 55 only ( end of code output), engine has compression and makes spark. After relieving fuel system pressure, I should hear the fuel pump run the next time the key is turned on, right? Well, I don't hear it! Which tells me either the fuel pump is out, or the fuel pump relay is out, right? Does anyone know the location of the fuel pump relay? There are five relays on the driver's side inner fender (under the hood); one plastic-cased and four metal-cased, all in a row. Okay, if I don't hear from anyone tonight, I am going to the library tomorrow to look up the location of the relay(do some of my OWN research - what a concept!). I mean, the relay is accessible and costs far less than the pump, so it's practically a lock that it's the pump, but the exercise in troubleshooting will do me good! Thanks for all the help - Chris
 
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Old 08-12-03, 09:19 PM
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yes it's one of those relays, which one or two that control the fuel pump is tough to remember, every year is different, some years have a fuel pump relay and an ASD relay that both control the pump.

the computer has no idea that you just pushed the schrader valve, to then actuate the pump. it should always actuate it. two seconds with the key turned on initially, then once it gets an rpm signal (cranking) to the computer, it should be always on.

photo copy as much as you can from the library, that information always comes in handy.

if i suspected a fuel pump, i would simply measure for 12 volts and ground at the fuel pump connector while someone else is cranking the engine, that would eliminate the entire electrical system (all relays)if the power is there. one step further, is to hit the bottom of the gas tank with a rubber mallet, your open palm or even your sneaker/boot while the engine is getting cranked. try to hit at the rear-center area, it's the same theory here as hitting a starter with a hammer, you're trying to jar the pump/motor into working. if it starts up the engine right away---you know what you need. yes--it's safe to hit your tank. i've replaced (on average) 30 fuel pumps for every one relay that i find bad


if you decide to replace the pump, hope the tank is under half full, it makes an easy job that much easier and also replace the fuel filter regardless of how old it is.

let us know what you find
 
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Old 08-13-03, 03:52 AM
Joe_F
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I agree. Autozone can also rent you a fuel pressure gauge which will help in the diagnosis too.
 
  #9  
Old 09-08-03, 11:43 PM
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Well, it's been a while since I posted on THIS issue. Turned out it was the fuel pump. Test light at the connector on the tank showed voltage when turning the key (my wife hates to help me troubleshoot when I'm under the vehicle and she has to get in, but she's a good sport and does it anyway). Dropping the tank is not something I'd want to do every week, but it was MUCH simpler than others I've done - pretty straightforward procedure that comprises maybe six steps in the manual. Soldering the connectors on the motor proved to be a challenge. Might have been a little easier if I had a real soldering iron/gun. Anyway, the van is back on the road again, strong as ever. My thanks to all for their input; you are the ones who make this great forum what it is. 'Til next time,... Chris
 
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Old 09-09-03, 06:23 AM
Joe_F
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Ummm, the new pump should be a direct fit with no soldering from what I remember. This is the old style Chrysler wire type hanger, but if you got a complete drop in unit from the aftermarket or Chrysler, it should have been a breeze.

I HOPE you didn't just cheap out and replace the pump and not the whole hanger .

Later models (modular style) included the fuel gauge sender on some applications. 1990 is a wire hanger though as I mentioned earlier.
 
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Old 09-09-03, 07:19 AM
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Joe - Yes, frugal as I am, I cheaped out. Pump was about $90, pickup filter about $11. I'm one of those who will take an hour to save a dime (if I'm working on mine). As for the soldering, I did it on the replacement because it had been done on the original. As I thought about it, it began to make sense. The soldered connection keeps the connection from coming loose (thus disabling the pump) and from possibly making contact AFTER coming loose (I'm thinking a spark in the fuel tank could be bad!). It's probably so much overkill, but hey,... Oh, this year model (03/1990) had two hangers in the fuel tank; one for pump, one for sender. By the way, when I dumped the fuel out of the tank, a small black plastic piece fell out with the fuel. It was about 2&1/2" long, 3/4" wide at the widest, and sort of shaped like a mushroom, with the stem hollow and the bore going through the "mushroom cap". Any idea what this is/was? The van seems to run fine without it, but if it's a critical part, I guess I should put it back on! Anyway, thanks for the help. 'Til next time,...Chris
 
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Old 09-09-03, 07:55 AM
Joe_F
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You really didn't save anything .

Case in point: I did my friend's 1991 Shadow pump, that's the later module style I was talking about.

He wanted to go to Pep Boys and spend $149 on JUST the pump there.

I got him the WHOLE hanger unit (which actually turned out to be the SAME $250 OEM part he was quoted at the dealer, had the SAME #s on it) for $125.

We were done in two hours flat including a couple of belly laughs and "Pass the wrench you putz, hurry up, I'm getting dirt in my hair. LOL".

Fact is, many of those pumps fail quickly .
 
  #13  
Old 09-09-03, 08:48 AM
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Just to satisfy my curiosity, Joe - did you find the hanger unit at AutoZone? I know how well you like them; they have got me throwing rocks at other parts places most of the time, too. I had to get my parts from Checker this time, though, because AutoZone was about two days out getting them in. I don't remember even checking on the whole hanger unit, but they probably could have got it. I think all it's got that I didn't replace is the "pulsator" and the plate/hanger assembly itself. BTW, what is the purpose of that "pulsator"? Thanks again - Chris
 
  #14  
Old 09-09-03, 09:04 AM
Joe_F
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The pulsator stops fuel pump vibration from being transmitted through the fuel lines and in some cases into the passenger compartment.

I bought the fuel pump at my regular, independent auto parts store that has been there since 1920 and gets mostly all of my business.

I have nothing against any auto parts store, chain or otherwise that sells quality product. There are good and bad independents and chains, and good and bad parts stores IN the chains and independents.

Choosing a good parts store is much like choosing a good restaurant. You like the product, service and prices. And you want all three .
 
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