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-   -   fuel injection question (http://www.hotrodders.com/forum/fuel-injection-question-40204.html)

beau5278 05-26-2004 05:59 PM

fuel injection question
 
Does any body have firsthand knowledge of how many fuel pumps should an '86 Mustang with a 3.8l v6 have.I have two repair manuels,Chilton and Haynes,they both say there should be a low pressure pump in the tank that feeds a high pressure pump that is on the frame near the fuel filter.Autozone and the local ford parts guy says there is only one in the tank.I'm confused I only have one in the tank,but I don't seem to have enough fuel pressure.:confused:

dmorris1200 05-26-2004 06:23 PM

Can you define "don't seem to"?


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chianesi 05-26-2004 06:32 PM

On the 3.8L there is only one (1) fuel pump. You need to get an inline fuel pressure gauge and go off the spec listed in the manual as far as what fuel pressure you should have. If it is low, first change the filter and try to blow out the line(s) with an air compressor. After you recheck the pressure and its still low, then get a new pump cause its probably wore out.

If the pressure checks out OK, then move to the throttle body and inspect/replace the injector or a complete rebuild on the TB if needed.

I can imagine with the year of the vehicle that alot of stuff will be out of specs.

Hope this helps!

dmorris1200 05-26-2004 06:36 PM

Quote:

Originally posted by chianesi
On the 3.8L there is only one (1) fuel pump. You need to get an inline fuel pressure gauge and go off the spec listed in the manual as far as what fuel pressure you should have. If it is low, first change the filter and try to blow out the line(s) with an air compressor. After you recheck the pressure and its still low, then get a new pump cause its probably wore out.
Don't you think checking the fuel pressure regulator might be a good idea before he jumps into a fuel pump, assuming he really is low on fuel pressure.

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chianesi 05-26-2004 07:03 PM

Its common knowledge to check the fuel pressure regulator after installing the gauge and checking the pressure, if it's not to specs. My apologies for not putting it in the last post. But if you read on you'll see that I meant replacing the pump as a last resort. Thanks!

beau5278 05-26-2004 07:04 PM

Thanks guys,I replaced the fuel pressure regulator when I got the car.I saw it run(if you want to call it that),at an idle it blubbered and carried on like it was getting way to much fuel.After replacing the reg.,it didn't want to start at all,the timing was screwed up,half of the plugs had fuel blowing up past the porcelain.I set the timing right,put in new plugs,and still nothing.i pulled the valve covers and checked the lift at the lifters,it was way below specs.Put in new cam,lifters,timing gears and chain.Now it trys to start if I open the throttle about half way,but it will only run for 2 or 3 seconds.If I pop the shrader valve on the throttle body,I only get little more than a trickle of fuel.

dmorris1200 05-26-2004 07:22 PM

Quote:

Originally posted by chianesi
Its common knowledge to check the fuel pressure regulator after installing the gauge and checking the pressure, if it's not to specs. My apologies for not putting it in the last post. But if you read on you'll see that I meant replacing the pump as a last resort. Thanks!
Never assume "common knowledge" on an internet forum. The first thing in Hotrodders guidelines for posting says to be clear and provide as much info as possible when asking for help. He did not provide any worthwhile diagnostic information in his first post. Now after reading his second post it is very possible he has a bad pump but he should still get a pressure gauge and verify it correctly. Most fuel pressure tester kits will hook up to his shrader valve for a quick accurate result. Sorry if I seemed harsh but I prefer to go step by step, seeing exactly how much a poster really knows and what steps he/she has done so far before diagnosing anything. Just the way I am. Doesn't seem right to me to go "could be this, this, this, or that" without even knowing what symptoms there are or what tests have been done to lead a person to form their own assumptions. Over the years I've seen to many unnecessary parts installed in cars because of inadequate diagnostics. Once again, sorry for being a bit sarcastic.:cool:

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chianesi 05-26-2004 07:26 PM

No problem

beau5278 05-26-2004 08:47 PM

the main thing I wanted to know with my original post was about the fuel pump.Like i said the books told me one thing and I know I didn't have 2 pumps.I really appreciate the info and I just don't have any firsthand knowledge of these little Fords.I just started messing with them some 'cause I think they are cool little hotrods.I picked this one up 'cause it is a convertible and pretty much unmolested but if this six doesn't wakeup pretty soon It might be time for a V8

2-manytoyzs 05-27-2004 12:19 AM

After market manuals are not accurate or specific enough for all car applications and they try to cover too many models just to sell a "manual". Also they have very limited useful information on specifics for diagnosing a problem, just general information.
Some Fords use a low pressure pump intank and a high pressure pump on the frame. Others use a frame mounted high pressure pump while others use high pressure intank Assembly. You have to go by what you have in your application.
dmorris is correct in his statement that the pressure is checked at the schreader valve.


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