Hi guys,

I knew I would have more questions about my Bronco - just not this soon.
94 351 good condition - I just did a tune up - plugs, cap, rotor, wires, filter, ETC. the gas mileage was going down.

I was driving home yesterday and my engine check light came on. I pulled the codes - they were -

332 - insufficient EGR flow (reader manual and Haynes)

542 - Fuel pump circut open connection - electronic control assembly to motor ground (according to the manual)

542 - Fuel pump secondary circut failure - PCM to ground (according to Haynes) which one is correct?

My questions - can I clean the EGR? $85-$140 for a new one. If so what would I use. The vacuum line looks OK. I'll try to check the EGR valve with vacuum today. Anything else I should look for?

The fuel pump circut - I don't know how to proceed - I am new at this so any help would be greatly appreciated!

Thanks,
Mark

 

the original vacum lines can become brittle and crack very easily so i suggest you check them all. replacing them with rubber vacum hose is recommended.

yes you can clean the EGR but i forget what to use exactly. occasionally the sensor on top of the EGR is the issue or again the vacum line.

as for your other codes i would make sure your battery cables are in really good shape and the grounds are good and clean. If you disconnect your battery for a while and then go take a good hour long drive and recheck codes to see if they come back.

just curious what plugs did you install?

 

Cleaning the EGR valve can be accomplished by carefully removing soot and carbon from the pintle and seat inside it. Its a tedious process if ther is a lot of crud built up on it as you cannot get inside the valve but to poke at it through the holes around the perimeter of the valve body. You can use cleaners but sparingly and nothing very harsh since the vacuum diaphragm is made of rubber and anything too harsh will vitrify the diaphragm and you are right back to spending the money to replace it.

I would suggest following Kem's advice FIRST though and make sure you didn't just lose the vacuum supply to it. Might want to check the EVP sensor as well as this is the monitor for the EGR valve. There is no PFE sensor in these trucks.

The literal translation of Code 542 is an open circuit somewhere between MAXI-fuse "O" in the under-hood power distro. and the fuel pump motor. Now the only problem with this is the simple fact that the power from fuse "O" runs through the inertial shut-off switch, and the pump motor as well as feeding pin 8 of the ECM. Now if the fuel pump circuit supposedly failed, my question is, did the truck stall? Because if it did not stall, then I would lean towards a weak ground or a problem with the feed to pin 8 of the ECM. The computer seems to think you have a problem with power to the fuel pump... do you really have a problem with power to the fuel pump? See what I mean?

 

It's unlikely that the EGR valve itself is bad. To check the EGR VALVE start the truck and let it run. Unplug the vacuum hose at the EGR and attach a piece of tubing in its place. With your mouth or a vacuum pump pull a vacuum on the hose. If the truck stumbles and almost or completely dies then the VALVE itself is fine and you'll need to look at the vac system (hoses, resevoir, solenoids, position sensor, solenoid wiring, position sensor wiring). If nothing happens then the valve really is stuck, or it and/or its plumbing is plugged.

 

Thank you - Kemicalburns, greystreak & mprice!

I will follow all advice and let you know what I find. Kem - I used Motorcraft SP-415 plugs. I normally use Autolite Platinum on my '78 F150. I will check everything, disconnect the battery and go for a drive.

Greystreak - the truck did not die yesterday when this started or today. The only time it died was on a recent road trip - ran fine for 7 hours and then it just quit. Nothing like being broken down in a town where you don't know anybody. Luckily I found a good mechanic and replaced the fuel filter. I did not check for codes then.

Mprice - I will check all vacuum lines and the vac to the EGR. When I replace the lines are they 5/32" like on my 78? I have not looked at this very closely.

Thanks again!
Mark

 

stay clear of the platinum plugs, ford motors do not like them and they are not a good conductor of electricity compared to cheap copper plugs. dont waste your money.

 

Thanks again everybody!

I started to check the EGR vacuum, pulled the elbow off the valve and you guessed it I was holding the elbow with a small piece of the green plastic line coming out of it. It was broken inside the rubber sleeve that was covering it. I put a longer piece of rubber vac line on it, connected it and no more engine check light. I don't think I did this when I was replacing everything but I might have.

Cleaned up the battery, the ground definately needed it. That is my fault all the way! I haven't been very good about checking things on a regular basis. I will change that. I am going for a drive tomorrow morning and will let you know if I get any more codes.

I plan on replacing all vac lines soon. Thanks for the info on plugs - I did not know that. I am keeping notes on everything I am learning on this site so I can refer to them when I need to.

Thanks,
Mark

 

the search works well also

 

I would like to thank everybody who helped me with this!

I took the Bronco for a long drive this morning and then checked for codes. Success!! I am starting a new maintenance check list for it - I have to admit I just got lazy because it always ran so good. With my '78 F150 I did a visual check and oil check every weekend. I will do the same with the Bronco. (I do check the oil)

When I replace the vacuum lines is it OK to reroute them to make them more accessible?

In the future I will do a little more trouble shooting before I ask any questions. It is my first vehicle with all the computer stuff, my first with auto trans and first with A/C. I have alot more to learn about this truck.

Thanks again,
Mark

 

I doubt the factory routing is the only possible way but it looks like a good safe route. Going around behind the intake keeps it out of anything spinning or hot.