I got a code for Fuel pump secondary circuit failure, how do you fix it? 1990 Aerostar 4.0 2wd with A/T and A/C

 

Here are some tutorials on diagnosis of fuel pump issues:

http://www.airtexproducts.com/AIRTEX...tex_TTS_09.pdf

http://www.carterfueldelivery.com/fu...diag_chart.pdf

http://www.rockauto.com/catalog/moreinfo.php?pk=296485-

A quick glance in my 91 manuals didn't find the specifics for the codes, but the above info should help you track down the problem.

 

The fuel pump is powered by a relay, and its secondary circuit is monitored by the EEC. The primary circuit also powers the EEC itself, so if that's out, the EEC would not come on, so no self test or codes. So the most likely failure is in the relay.

When you first turn the key on, do you hear the click of the relay? If not, it's probably the relay.

Do you hear the pump run for 2 seconds? Does the engine start now? If either of these are "yes", then the problem is more likely with the sensing circuit.

 

Yes, it does run and you can here the pump come on. The van failed to start one time on my wife, but running fine sense. Just ran the codes last night and got a 95 and 66. ran them later and got 77?

 

Lasst time I got that code, I ended up getting stranded 250 miles from home because the fuel pump died. While it doesn't tell you whats going on, it often means that the fuel pump is drawing more current than it should. That is often a sign that it is in the early stages of dying. However, the relay is cheap and easy to get to, so try that first. If the relay fixes it, great!

If it comes back, look at a new fuel pump. When replacing the fuel pump, use genuine Motorcraft only. I went through 3 different fuel pumps before I got the Motorcraft one. The reason is that because these vehicle have gotten older, many of the aftermarket choices have gone away, so most of the aftermarket ones out there are all actually the same thing, and that is the one made by the low bidder. Then they slap some brand name on it and call it good.

 

Motorcraft pump with new sender and float, $235.79 at Rock Auto. The cheap one is $49.99 for pump only.

You can also get good name brands for only a few bucks more without having to get stuck buying the whole assembly.

There could have been multiple reasons that the 3 pumps failed on you. I look at this this way, many manufacturers have simular pumps because the fuel injectors have simular requirements when it comes to pressure and volume. The failure problems are simular in all manufacturers so why would a Motorcraft pump be superior to a Carter or a Bosch?

As an example, consider locks for cars. I am a locksmith so I am familar with the locks. Often there are several OEM suppliers that supply car locks to the manufacturers. When you buy a lock at the dealer it might come in a box or bag that says Motorcraft, or Mopar, or GM on the outside, but it is identical to the one you buy at the locksmith shop that comes in a bag or box stamped Briggs and Stratton (Yep, the same folks that make lawn mower engines.)

Sometimes the aftermarket stuff is better and less prone to failure. an example here is the Ford Focus. the Focus had an ignition cylinder made by HUF (a German company that makes locks for Mercedes and other Euro manufacturers.) The design was poor and the locks were prone to fail.

Ford continued to sell the Huff brand under the Motorcraft badge and they still had cronic problems. Briggs and Stratton however redesigned the lock and eliminated the cause of the failure, so it was a much better replacement option.

While locks are not fuel pumps, the same logic applies.
The aftermarket offerings are made by different companies, and they very well be the company that sell the same part to Ford to sell aftermarket. They might also be the in company one year and the out company the next. And yes, I will concede that some aftermarket companies are the typical "brand X" shucksters that market junk, and hope you loose the receipt or sell the car before the warranty expires because their parts are never going to make it, but many will provide a equal if not superior product for a whole lot better price.

After all it is not rocket science. A fuel pump is a small electric motor and a piston, diaphram, or some sort of rotary vane set up. The ability to make quality pumps in a cost effective manner is not a mysterious technology.

 

The original fuel pump on my 87 Mustang died in 94, while I was 35 miles from home on a dark night. I should have realized something was wrong when I heard it sounding coarse, as in not a smooth hum. I replaced it with an aftermarket unit purchased from a hot rod shop; just the pump, but it did come with a new strainer sock. I can't remember the brand. It was supposed to be higher capacity than stock, for those who want to soup up their engines. It's been working fine to this day. The biggest difference I can tell when it's running is that it has a smooth hum that is a lot quieter than the noises that the stock pump made most of its short life.

Pump replacement on the Aerostar should be easier than on a Mustang. In either case, you want to leave as little gas in the tank as possible, either by using it up or siphoning it out. You don't have to completely drop the tank on the Aerostar, just loosen the straps and lower the outboard side of the tank enough to get at the mounting plate for the pump/sender.

To prevent future pump failures, never let your tank run too low. The Aerostar's tank does not have baffles, just a depression where the pump pickup sits in. With a low tank, and fuel sloshing around, it's easy for the pump to suck air. The pump uses the recirculating gas to keep itself cool, and sucking too much air will burn it out.

 

Where is the relay for the fuel pump? The pump still sounds good and was replaced about 6 years ago, may need to again, but the relay has not been done at all.

 

All I know is my original fuel pump lasted 160K+ miles, then I went through three before it reached 200K. The new pumps would whine and scream shortly after they were new. They made excessive noise, and when I would haul heavy loads, they would get louder. Then the output and flow from them would start to drop, and the vehicle would start leaning out under load because the fuel pump could no longer keep up. There was no debris in the tank, and the fuel filters were replaced each time, but were not plugged. Finally replaced the last one with a Motorcraft one, the van became like new, more power than it had in a long time, no screaming sound, none of the problem I had with the aftermarket ones. Go figure, the OEM one that came on the van outlasted any of the aftermarket ones by a factor of 16:1. I ran the last Motorcraft pump another 40,000 miles before the van was totaled. The aftermarket ones were not that much cheaper, especially not considering installation costs, hotels, and out of town repairs.

 

OK so there was some reason that the 3 pumps you put in were failing. If you ruled out debris, there could have been some problem with the wiring harness that may have been causing extra resistance, it could have also been that you got three bum pumps in a row from different production runs, but that as I see it is the least likely reason.

 

According to my 91 service manual, (I suspect the 90 is the same.) the fuel pump relay is located "on the front of LH fender apron, on relay bracket."

Looking at the diagram it looks like you should take out the battery, and look just behind the starter solenoid. There is a box that has 4 relays, and some (3) test connectors attached. The fuel relay seems to be the farthest forward relay. The output is the pink/black wire that runs to the fuel pump via the inertia switch.

If you read this:

http://www.carterfueldelivery.com/fu...rt/TEC1620.pdf

Here is a really good video (If you don't care for the music, you can mute the sound and not miss anything.) to explain voltage drop testing:

YouTube - ‪Auto Repair: Voltage Drop Testing: A Powerful Electrical Testing Method‬‏

It will show you how to measure the voltage drop in all the wiring between the battery and where ever you check along the wire. If the voltage drop is too great, you are getting less voltage to your fuel pump due to the higher resistance and that will take out the pump in time.

 

Thanks Roger, I will check it out this morning.

 

So explain to me why a factory fuel pump worked flawlessly. My van already had the updated fuel pump harness installed under recall long before I bought it, the original owner took care of that. As I said, the factory pump lasted a long time, I wnet through three aftermarket ones in under 40,000 miles, then went another 40,000 miles with an OEM one without any further problems. Its not a case of three defective parts in a row, its a case that the common aftermarket units are not made to meet OEM specs, they are designed to meet a budget. They require more power to run than the OEM pump, they don't flow as much fuel, they run hotter, and they struggle to build the same pressure that the OEM pump would.

To me there is no comparison. If you are going to replace just the pump however, instead of the entire assembly, you can use performance pumps with good results. The Walbro 250 lph pumps are ok but noisy, and the TRE 250 lph pumps are electrically efficienct and quiet and a little cheaper than the Walbros.

 

I'm sure my replacement for my Mustang was a "performance" pump, as it had higher flow rating than stock. I think it was 110 lph, vs the stock was 88 lph. If I could find it again, and it would fit in place of the pump in my Aerostar, I would definitely use it as a replacement.

When I was working at Ford, one of the tests we did was on the then-new TBI systems. It also used an in-tank pump. Under steady-state operation, the pump only ran at 9 volts through a dropping resistor. When you started the engine, or when you were accelerating hard, a relay kicks in to short out the resistor to give it full 12 volts. We analyzed the noise spikes generated by the relay when it switched off, which would some times reset the EEC. The pumps we used on the bench were really sensitive to heat; they generally didn't last more than 10 minutes running dry before they started to make noise. Those were, of course, real Ford parts.

I don't think the current EEC systems have a low voltage operating mode. But an obvious clue here is that if you hear your pump getting noisy, it is time to get a replacement, and schedule a replacement. Also, and I reiterate, never let your fuel tank run too low.

 

Got an airtex in my 96 for 2 years now for $30 or so. I would never spend big bucks for a pump. IMO. Plus my tank is never over 1/4 full.


Dick