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Discussion Starter #1
My friend has a 1988 e 150 van with a 5.0 in it, and it is running rich at idle and take off. We changed the o2 sensor and it didn't change.It got so bad it fouled the plugs. We changed the plugs and did an oil change .I am not up on the 5.0 computer controlled engines. What am I overlooking?What senser should I look at?
 

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I'm not up on the 5.0 stuff but in the past I've seen the fuel pressure regulator go bad and suck large amounts of fuel into the intake trough the vacuum line that controls it.
Take the vacuum line off the fuel pressure regulator and see if it has fuel in it. It should be somewhere on the fuel rails that feed the injectors.

I'm not even sure if your car has one or not, It's been a while sense I worked at a repair shop.
I've seen people spend all kinds of money on parts that don't need to be changed. When I worked full time in the business I always checked the parts I thought were bad. If you get a good Manuel it will give you the procedure on checking the components in the system.

Hope this helps.

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<font size=-1>[ This Message was edited by: 393Clevor on 4/29/02 9:14pm ]</font>
 

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Discussion Starter #4
I still have a very rich condition,it fouled another set of plugs and the oil is gassy.I changed o2 sensor and checked fuel reg for leak in vacuume hose.Anyone have any other ideas?HELP!!!!!
 

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With it running pull the vacuum line off the reg. See if any gas comes out. Also put a gauge on the system and see if it holds any pressure when you shut it down. You may have a bad injector that's letting fuel dump all the time.

The injectors should have full power all the time it is controlled by the ECM and it uses the ground to control the injector. I have seen cars that have a full ground to the injector because of a wire that's shorted to ground somewhere in the harness. This will lit the injector dump full fuel all the time and give a rich condition at idle.

Could be the temp sensor is giving a cold reading to the ECM but I don't think it would flood the motor to that extreme.
 

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Take a screw driver (a long one) and put the screw end on the injector and the other end to your ear listen for a click sound. They should click loud enough to hear them without the driver but you can clearly here them using a screw driver. If you have one that does not click I would say that's a good place to start. It may not be the injector but a wiring problem somewhere if one is not clicking.

Keep us posted.
 

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Discussion Starter #7
I have to change the plugs and oil again to get it running.It seems to be running rich all the time.I cranked over the engine with the plugs out and it looked like a mist of fuel was coming out on the compression stroke? Maybe leftover fuel?Will a bad map sensor give me this problem?If I disconnect any of the sensors will this help eliminate the rich mixture?
 

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I don't think the MAP will do this.
You can turn the key on and if the fuel pump comes on you can pull the vacuum line off the reg. to see if it leaks gas from the reg. You can also suck on the vacuum line that goes to the reg. you should not get any fuel from the vacuum side of the reg.

Also crank it over and listen for the injectors to click it does not have to run to hear them. Be very careful there is a lot of fuel in there by what you have told me. If you can unplug the coil power wire before you do this. That will shut down the spark.
 

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Discussion Starter #9
I had the vacuume line off of the fp reg it did not leak fuel while cranking or tuning the key to on.I can hear the fuel pump come on as soon as the key is turned on, that sounds normal.Will a bad tp senser cause my fuel problems?I'm running out of ideas and patients with this efi stuff!!
 

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I dont think you have one injector bad, cuz your fouling all of the plugs. Check the coolant temp sensor, not to be confused with the sending unit for the guage. IF it has gone bad, the engine will not know the correct engine temp, and can give you all kinds of wierd fuel mixtures, but usually it causes a very rich condition. If you dont have a code scanner, pick one up. They are cheap and very handy for finding problems. A bad coolant temp sensor should trip a code too.
 

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Sounds to me like you have a bad fuel pressure regulator. They wont always leak through to the vacuum hose. Sometimes they will just allow way too much pressure which makes the engine run rich. You need to get a gauge on it and check the pressure. At idle it should be 30-45 psi.....approx 30 with the vacuum hose on and 45 with it off. A bad MAP will can cause it to run rich but not usually that rich, same as the ECT. A bad TP will usually just make it idle high.
 

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Does it run rich hot and cold or just hot?

If it is the same, it's likely a temp sensor, but which one and whether it's the sensor of the harness needs further investigation.

If it is rich only when cold, then you can rule out temp sensors.

I now this post sounds like a step back, but I never saw any mention of the temps.
 

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Discussion Starter #13
It seems to be running rich all the time.This problem came shortly after I changed the water pump on it.Last nite I had to change the plugs and oil for a second time,after that I fired it up and it was loading up rigt away,so I sut it down.I think I will change out the temp sensor.
 

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I've got an '88 5.0 Mustang. Just got it back together and was having the same problem... Rich all the time(hot or cold)... Had to turn up the idle all the way to get it to run. Bucked like a bronco (not the 4wd kind) at anything but idle and 75 - 100% throttle.

Read this post and started checking out all the items... Found a disconnect on the MAP vacuum line. Fixed that and it's running like a champ(knock on wood). My bet is on the MAP sensor / vacuum line.

Good Luck!
 

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Well, if it ran good before you did the work I would check the wiring. Make sure all the ground wires on the intake and anywhere else they put them have a good connection. In the past I have seen a bad ground do all kinds of strange things and it ran good before the work so I would look over what was done, check every wire on it.

Just a thought.
 
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