84 SVO frying fuel pumps

[IRSmart21]

Hey guys!

I first want to thank everyone for the wealth of knowledge that is posted on this site. It has been a life saver on multiple occasions.

That said, I need some insight to help me work out an I've-seen-it-work-but-logically-it-makes-no-sense-to-me situation.

Let me start with my situation. I have an 84 1C that used to belong to NinjaBOY. I wouldn't trade this car for anything in the world. She is a thrill to drive. Without going into too much detail, she wound up sitting for about 3 years with an engine issue. In the last 2 months I finally got her running again. While getting her back into working order I wound up making a few “upgrades”. Those include:

Replaced the rubber/plastic fuel lines with a set of hard lines out of a ’92 mustang LX
Replaced the fuel rail to match the new hard lines
Upgraded the alternator from the stock to a 130a 3g from a Taurus
Upgraded to a serpentine setup from an ’88 turbo coupe

When I first fired her up in July after sitting, I had a problem with the fuel pump not wanting to run. It initially started for a short second and then died. I had my wife assist me with rolling the key while I beat the tank with a hammer. This method did get the pump running and she has been running strong until last week. I drove her for a full day, parked her, and then went to drive her again that night and the pump wouldn’t kick on. Tried beating the tank again and it didn’t work. So I went ahead and purchased another Walbro GSS340 and replaced it over the Labor Day weekend. Once again, she was back on the road……until today. I started her up, let her warm up for a bit and then started driving to work. I didn’t get a mile down the road and she died AGAIN. I can hear the relay clicking under the driver’s seat, so I know it is sending electric back there, the pump just won’t kick on.

SO, here is where my request for help comes in and where this post might get a little weird. Back in the late ‘90s my parents had an ’87 Ford Aerostar that, on at least four separate occasions over the span of a few months, died in the middle of us driving with a dead fuel pump being the culprit. My parents eventually took it to the local Ford dealer to have it fixed. The suggestion/solution given to them by one of their senior mechanics was to replace the distributor stator/pip module. As off-the-wall as this might have sounded, it did indeed fix the problem. They never had another fuel pump die in that van as long as they owned.
I would have taken it as a freak solution IF one of my dad’s coworkers at the time hadn’t had the identical issue with his Aerostar, and at my dad’s suggestion, had the stator replaced and he never had another problem with his pumps dying on him.

Now, knowing what I now know about the electrical systems in these 80’s Fords, replacing the stator makes NO sense to me AT ALL as to how this actually fixed the problem. However it worked twice in the past on two different vehicles that, even though were V6 engines, essentially had the same distributor and TFI setup that the SVO’s have. Does this make sense to anybody here as to why this would fix this problem? I am most likely going to wind up replacing the whole distributor in my SVO to replace the stator for simplicity’s sake and will report back if this does fix the problem.

Please let me know if you think this solution sounds completely bizarre or if you have seen this work for yourself or others in the past.

If you might have any suggestion as to what else might be causing the problem, that would be appreciated also.

Thanks for any replies given!!

[SVOeric]

So it's not so strange. The PIP signal does a couple things, the computer looks to the PIP to decide when to fire the spark, but it also looks to the PIP signal to run the fuel pump.

When you turn the key on, the computer fires the pump for it's initial 5 seconds, to get fuel pressure up, in case it has fallen off. After that, the computer looks to the PIP signal to maintain the pump. If the PIP signal stops from the distributor, the computer will kill the signal (power) to the fuel-pump relay. What you don't notice is , you're losing spark with this as well.

Fair chance you may see a 'loss of pip' code if you check codes on the computer

Also a few other items that are worth checking.

• 84's used 2 pumps. A low pressure in-tank pump, and a high-pressure pump. when you replace the low-pressure pump with a high-pressure pump, you should generally remove the 2nd high-pressure pump. it's right in front of the rear-end on the frame rail. You may have done this, but you didn't mention it.
• 84's use high resistance ground wire on the low pressure pump. Make sure you run a new GOOD ground wire for your high-pressure pump.

[svono50]

Eric pretty much hit it on the head with the control of the fuel pump, so replacing the PIP could be the actual solution. Also note that the PIP will generally go 'open circuit' when heated up, but work fine when 'cold', which is a classic failure mode of a PIP...ask me how I know! It is also highly likely no code will be recorded, so don't be shocked if you don't find one.

Easiest way to replace a PIP is to swap in a rebuilt/spare dizzy, but you can replace it outright. You just need a press to remove/install the drive gear on the shaft, which I farmed out to a local auto repair shop when I changed mine out. BTW, your pump you pulled out was likely just fine, so hopefully you didn't toss it yet.

[IRSmart21]

Eric,

Thanks for your reply. The system is a single high-pressure pump. I am currently using the existing harness that I am assuming used to feed the low pressure pump. Is there a way for me to check the condition of the current ground (resistance wise)? Where is the ground wire located that I would need to check?

[svono50]

I know the wire is located in the tire well down to the pump connector...if my memory serves me right. You should be able to search and find it on here, as I know it has been discussed in the past. Unfortunately I have an 86 and haven't had to convert, so I don't have any direct experience.

[IRSmart21]

Ted,

Any issues that I have had with the SVO have been quite the opposite. I tend to have more random idle issues and "drops" or mis-fires when the car is cold and she runs like a champ when she is good and hot.

I will probably go the route of replacing the whole dizzy. It has been advised to me that if I am going to put in a new dizzy that I need to use the old gear off of my original one. This is said to prevent the metal shavings and such from wearing off the new gear into my motor because the two existing gears already match up well.

Would you suggest this as well?

As far as the pumps are concerned, I am almost certain that they are dead. Unless I am missing something, the original one wasn't working and didn't work of three days leading up to the replacement. When I put the new one in and the new one worked until today. Are you saying that it might not be getting ENOUGH voltage? Is there a way to test the original one that won't damage it to see if it is still good short of putting it in the tank and seeing if it will turn on?

Thanks guys for your replies!

[SVOeric]

The resistance wire is fairly easy to see, it's a little different 'feeling' than the standard wire. The best thing to do is put a new ground wire from the end of the pump harness.

This pic if from an 86, and I'm pretty sure it's close to the same on an 84, but the connector that connects to this connector, should run a ground to chassis.

[svono50]

Ted,

Any issues that I have had with the SVO have been quite the opposite. I tend to have more random idle issues and "drops" or mis-fires when the car is cold and she runs like a champ when she is good and hot.

I will probably go the route of replacing the whole dizzy. It has been advised to me that if I am going to put in a new dizzy that I need to use the old gear off of my original one. This is said to prevent the metal shavings and such from wearing off the new gear into my motor because the two existing gears already match up well.

Would you suggest this as well?

As far as the pumps are concerned, I am almost certain that they are dead. Unless I am missing something, the original one wasn't working and didn't work of three days leading up to the replacement. When I put the new one in and the new one worked until today. Are you saying that it might not be getting ENOUGH voltage? Is there a way to test the original one that won't damage it to see if it is still good short of putting it in the tank and seeing if it will turn on?

Thanks guys for your replies!

As for the dizzy gear, I too have heard of issues with the reman gears, but also non-issues so I can't really answer that question. Hopefully someone else here can chime in on their experiences. If you go to the trouble to pull the OEM dizzy gear off, you might as well rebuild the OEM unit. Once the gear is removed, the shaft can be pulled and the PIP replaced, so your choice on which route to take.

With your pump issues, I would have to ask about the source of your pumps? If they are Walbro units, are you sure they are not Chinese knock-offs? There are a bunch of them out on the market and all over Flea-bay. The only place I personally trust getting a real Walbro unit from is APE (Auto Performance Engineering). They were one of the first online Walbro wholesalers and have been very vigilant in making sure their supply of units are genuine and not knock-offs. I ran one of their 155lph units for 10+ years and have been running one of their 255lph HP units for a few years now w/o any issues.

The resistor wire will lower the voltage that the in-tank pump is seeing and therefore reducing its output. That should not effect the life of the pump, only lower its capacity. The resistor wire starts a few inches up from the floor grommet in the tire well harness. The pump's ground wire is black and splices into a white wire...the white wire is the resistance portion. You can splice into the junction between the black/white wire run with a 12 gauge wire and run that new ground wire to a known good chassis ground. There are a couple of chassis ground wires along the rear body panel by the tail lights that you can connect to. This will help the in-tank pump get proper full voltage and help your on-boost performance.

As for testing the original pump, you can test it out of the tank. Running it for a couple of seconds in your hands won't hurt it. You can get a couple of jumper wires hooked up to your battery and touch them to the pump's terminals. Hold onto the pump as it will jump a bit when powered on.