Bad fuel injector or bad fuel regulator?

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Old 10-05-11, 08:21 PM
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Bad fuel injector or bad fuel regulator?

I have a 1991 Mercury Topaz, 2.0L four cylinder, four fuel injectors, and I'm not sure which of the two possible problems could be causing the car to struggle when starting.

After the car has been sitting from being ran, even after about ten minutes, it begins to become hard for it to start. I have to pump the gas peddle a little bit while starting the car to finally get it running, then I have to keep the RPM up until the car can hold its own. If I don't keep the RPM up, it shuts off, or when I barely keep it up, the car shudders for about ten seconds than normalizes. I understand that the engine/or a cylinder is being flooded, but what I don't know is if it's a bad fuel injector(s) or a bad fuel regulator, and also how to check to see if it's either of them.

If anyone could help me figure out if it's a bad injector(s) or a fuel regulator, how to check to see if one of the parts is bad, and even possibly of how to fix them.

Thanks!

David
 
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Old 10-06-11, 02:03 PM
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1. why do you "understand" that spark plugs are being flooded? have any proof to that?
2. sounds like idle speed control issue with maintaining idle.
3. if it's "hard to start" - how does it manifest itself?
 
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Old 10-07-11, 07:53 AM
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How's the coolant temp sensor? Does it need to be replaced? I don't know the specs on the coolant temp sensor, but if you put a ohm meter at the terminals of the sensor, the ohms should/will increase as the coolant temp increase. Coolant temp sensor could be sending the ECM incorrect readings during a engine start condition.

To check the fuel pressure regulator you will need to hook up a fuel pressure gauge. With the gauge hooked up, disconnect the vacuum line going to the regulator (while the engine is running) and see if the pressure goes up. With the gauge hooked up, you can also see how quickly the pressure bleeds off after shutting the engine off.

Try this as a diagnosis, take a pair of vise grip and carefully crimp the fuel return hose from the regulator. Let the engine sit for the allowed time and with the vise grip still connected go ahead and start the engine. If it stumbles and stalls then you know it's not a fuel pressure regulator issue.

I also wouldn't think it's a fuel injector problem. Even though injectors can intermittently act up, they usually act up in all driving conditions. Not just when re-starting the engine.
 
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Old 10-07-11, 09:21 AM
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As a side note, pumping the gas pedal on a fuel injected car doesn't cause flooding like on a carburated engine.

Might not be flooded or running rich; could be the opposite - too lean. In addition to the other items mentioned, fresh fuel filter wouldn't hurt unless you know it's been replaced recently.

Other tune-up items good? Plugs, cap, rotor, wires?
 
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Old 10-07-11, 09:44 AM
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I absolutely think it could be an injector (or injectors)....leaking...not really acting up. It's a 91 so it could easily have 200,000 miles. Injectors can wear out and leak after the engine stops, esp with the heat under the hood after being driven.

Sounds like one or more could be leaking down into the manifold/cylinder, making it hard to start and causing rough running til it burns off.

If it doesn't do it after sitting overnight...that would be an even better indicator.

Odd...Autozone doesn't show a 2.0L engine...just two variants of a 2.3L. And injectors aren't cheap.
 
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Old 10-07-11, 11:15 AM
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but O-rings are. And it's what most likely leaking, if that's the case. Now, my experience with those Fords is - buy O-rings from dealer, as regular O-rings do not have right shape and do not seal. set my engine on fire because of that.

for what it is, it might be simple DIY injectors cleaning, if one or 2 are stuck open.

otherwise, we are at standstill - we have no feedback from end user and are wild guessing.
 
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Old 10-07-11, 11:54 AM
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Hmmm...but aren't the O-rings what seal the injector to the manifold? To prevent extra air from getting in?

Dunno why that would cause the symptoms of a "flooded" engine?

Agree a cleaning might be the first thing...also agree we are just WAGing at it w/o some feedback.
 
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Old 10-07-11, 05:31 PM
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found handy thing:

So, how do you test injectors? Whether they are sticking, or leaking?

Well actually, it's pretty simple. What you need is an "injector tester". GM calls it the J39021. You can find ones that work similar to it on ebay, and the like, and typically cost between $80-$300. They look like this:

http://www.thepartsbin.com/cartools/images/otc-3397.jpg

I haven't found a place that rents them yet, but I'm sure SOME place out there will yet you borrow one. Autozone and Advance Auto do not however.

Anywho, once you have one, the directions are simple to follow. What you do is connect a fuel pressure gauge to the shraeder port (on the fuel rail), pressurize the rail (I don't know how this is done on the caddy, but it may be as simple as punching a few buttons on the instrument panel, or it may involve placing a jumper in the ALDL port) by turning on the fuel pump for a couple seconds, and seeing what it does.

If it starts dropping really fast (like a couple PSI/sec), then you have a leaking injector(s), or a bad check valve. You can check for the leaky injector by removing the fuel rail (everything still connected, do NOT remove the fuel lines or anything, just unbolt it, and pull straight up). Repressurize if necessary, but you should see a steady drip if it is the injectors. If not you have other problems.

NOW, assuming when you pressurized the fuel rail the first time, that it DIDN'T start droping, and held fairly steady, now you can use the injector tester. (reinstall the fuel rail now)

The process is simple,
1) Pressurize the fuel rail by energizing the fuel pump for a few seconds.
2) wait 2 seconds for the reading to stabilize
3) Record initial fuel pressure (should be about 39-45 psi)
4) Connect injector tester, and push the test button.(This will pulse the injector for a set amount of time)
5) When the injector stops clicking, immediately write down the fuel pressure (varies, could be 20psi or 30psi or so)
6) goto 1, repeat for all injectors

Now, average all the pressure drops you wrote down.

Example -
1) 20psi
2) 21psi
3) 23.5psi
4) 22psi
5) 21psi
6) 20psi
7) 21psi
8) 18psi

Average = 166.5/8 = 20.81
Any value more than 1.5psi off from this average is considered "bad". So,
Anything above 22.3 or below 19.3 psi is bad, and needs to be cleaned or replaced. In this case, #3 and #8 need to be replaced.

Keep in mind it will take some extra effort to start, because your engine how has a healthy dose of raw gas in it's cylinders...
 
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Old 10-07-11, 08:21 PM
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The engine is a 2.3L, not a 2.0, I was thinking of my Chrysler Laser on that one. I have had a friend of mine, a master technician, state that it could be a leaking injector(s) of fuel regulator. I haven't tried the vice grip test yet, but that's something I will try out soon.

I agree with Gunguy45 that is could very possibly be an injector or two. The car is a 91, only has about 135XXX miles on it, and hasn't given me any problems until recently. I do a lot of highway driving, about 400 miles round trip every weekend or so, and for awhile there the car was running on the edge of overheating due to a failing water pump. I don't know if that type of heat, of long durations of time, could effect injectors.

Also, since I found a gas station that sells Super Unleaded gasoline for the same price as normal unleaded, I have been burning the super instead of the normal. I've done this before and never encountered any problems, but perhaps the higher octane gasoline has slowly affected something?

Mentioned by ukrbyk, a idle speed control issue could be an issue, but since the car doesn't fully start unless I press that gas petal a little bit, once started the idle is fine, and starts up fine when shut down briefly, I don't think it could be that.

Tune-up wise, the car has new cables, spark plugs, and a fuel filter. The old fuel filter would cause the cause to bog down when stopped or accelerated hard.

I believe the issue is a simple one, most likely either the regulator or the injector(s). It's rare for older cars to have unusual or uncommon broken parts that cause symptoms, usually it's just a typical part. For advanced/new cars, electrical or uncommon parts are more often the problem for symptoms and problems, heck I heard that a dealer sold a lady a car that everything was doubled (she would travel four miles, but the car would say she traveled eight, it would tell her she is going 140 when she's going 70, etc.) haha, so chances are my car is just doing what old cars do best.
 
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Old 10-08-11, 05:04 AM
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Someone correct me if my memory is faulty, but on the subject of the regulator, isn't one sign of a bad fuel regulator having fuel on the vacuum hose side when you pull the hose off? If that's the case, quick item to check and fuel leaking past the regulator diaphagm and being sucked into the engine wouldn't be doing good things.
 
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Old 10-08-11, 07:15 AM
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I know this may sound dumb....but in addition to any other testing...after you drive it next time, put a brick or something on the gas pedal after you stop. That will hold the butterfly open and probably allow any leaking fuel to evaporate better. Basically thats what you are doing by "pumping" the gas.

You may have missed me asking, but what happens if it sits overnight or longer...same issue?
 
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Old 10-08-11, 08:03 AM
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Just don't turn the key before removing the brick!
 
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Old 10-08-11, 09:33 AM
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only has about 135XXX miles on it, and hasn't given me any problems until recently. I do a lot of highway driving, about 400 miles round trip every weekend or so, and for awhile there the car was running on the edge of overheating due to a failing water pump.

mileage does not sound too bad for injectors to fail. question is - was cheap fuel used a lot? as that's a known cause of buildups along fuel lines, filters, injectors, etc.
I'd prolly safely say that overheating engine does 2 things:
1. cakes residue faster than a normally running one
2. cakes and damages rubber grommets, seals, rings, etc.

of course, my all time favourite:
DIY Fuel injectors cleaning - YouTube
 
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