Throughput of SC fuel pump

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GRWeldon

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Well, I pulled the rusted-out hulk of what used to be a fuel pump out of my SC tank today. I know for a fact that it hadn't been in there more than 10 years! :)
It was so rusty that chunks fell off it in to the tank. Of course I had just put in 5 gallons of 93 octane in. The tank was bone dry before that. I recovered most of the fuel and I'll have to filter it before putting in back in. There was so much crap in the tank that I had to flush it. I stuck the wand of a pressure washer on the inside (2100psi) with a wide angle tip. The water that came out was FULL of rust chunks.

Anyway, the reason for the post is that when I bought the car, the previous owner put in a 119 LPH walbro pump. It was written on the duct tape he used to re-secure the aluminized padding back over the tank vent. The rusty hulk I pulled out was one I'd put in around 2015. Seeing the volume of the pump I pulled out in 2015 written on the duct tape (I didn't remove the tank completely in 2015) got me curious. When I ordered the new fuel pump last night I checked the part number for a 96 4.6 and then for my 94 SC. They were the same part number. Today I looked up the specs of the pump I ordered and it listed the minimum flow rate as 18 gallons per hour. This is only 68 liters per hour. There are two different ones sold on SuperCoupe Performance, a 190LPH and a 255LPH. With the one I'm getting from O'Rielly being only 68LPH, should I be concerned? MY SC is completely stock.
 
On the SC, the manifold pressure acts against the regulator and increases the pressure under boost above what a NA engine would see.

I would not use the 68lph on a SC.
 
IIRC, those were the first cars to upgrade to the 255lph Walbro. That's what everyone has recommended, since the old place started; you just have to be sure to get a real one.
 
I have a crank but no start condition on my SC. Suspecting cam or crank sensor but I'm shooting in the dark. I thought I remember reading that the tach won't register when cranking...wondering which one that is?
 
Over at SCCoA they’re always talking about bad crank sensors. No expert here but I’m sure the more knowledgeable people will chime in.

Joe
 
The main job for the cam sensor is helping get the injector pulse on the right stroke, which saves a couple revolutions of cranking during startup.

The crank sensor is the important one; it's how the PCM knows when to deliver spark. The SES light will stay on when cranking and the tach will be dead if there's no CKPS signal. You can also confirm by checking for spark.
 
theterminator93 said:
The main job for the cam sensor is helping get the injector pulse on the right stroke, which saves a couple revolutions of cranking during startup.

The crank sensor is the important one; it's how the PCM knows when to deliver spark. The SES light will stay on when cranking and the tach will be dead if there's no CKPS signal. You can also confirm by checking for spark.
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Thanks for the info. Crank sensor is not dead. Tach shows revs when cranking. I could start another thread but I'll try here first. Question 1: I found the Schrader valve on the fuel rail. If I remove the core and cycle the fuel pump a couple of times, shouldn't I see fuel come out this valve? I did not. I removed the fuel filter. There was fuel in the line. I blew through it in the direction of flow. Question #2: Should I feel resistance to the force of air going through? I had to blow hard to get air through.

I did order a fuel filter locally, should be here tomorrow. I'm thinking that if there's no fuel at the rail and the filter takes effort to blow through, possibly could be a plugged filter.

I'm assuming the only thing left in the chain would be a seized/plugged/rusted fuel pressure regulator? I don't even know where that puppy would be. If a new filter doesn't allow fuel to get to the rail, I guess I'm checking there next.

Edit: on a whim I decided to cycle through the pump a couple of times with the fuel filter removed. I expected to find a bit of fuel in the drip pan. I did not.i can hear the pump come on, then shut off after about 2 sec. No fuel at the tube that comes From the tank.

I just installed the pump this morning. I've done at least 3 pump replacements over the years with no issues. I guess I'm going to have to pull the pump and look further. I hate pulling the exhaust on these things. I almost checked to see if it would start before putting it back on. You bet I will this time...
 
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One way, you're blowing thru the pump; toward the rail should not pass air at all, unless you remove the schrader valve. Fuel pump failure is likely, at this point, and there are shitloads of fake walbro's out there now. hitting the key with the filter loose, with the tube to the tank in an empty bottle will show pump operation.
 
Grog6 said:
One way, you're blowing thru the pump; toward the rail should not pass air at all, unless you remove the schrader valve. Fuel pump failure is likely, at this point, and there are shitloads of fake walbro's out there now. hitting the key with the filter loose, with the tube to the tank in an empty bottle will show pump operation.
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Yep, see above post. I didn't see your addition. Fuel pump comes on but no pumping. Only 4.5 gallons in a bone dry tank, that should be enough, eh?
 
Well, I put the 68LPH pump in, I won't be driving the car for several months but I wanted to make sure that mechanicals are alright. Funny thing is the pump comes on but nothing comes out. I have to drop the tank again...shit!
 
It happens. There's a special piece of hose that get's buried in fuel; some pumps come with the wrong kind, and it dissolves.
 
That should be enough. If you can hear the pump, and no gas, its either dead, of the line in the pump. :( these pumps have gears, like our oil pumps. IIRC, there's a shear pin if the gear siezes. Anyway; you have a fuel pump replacement in your future.
 
Grog6 said:
That should be enough. If you can hear the pump, and no gas, its either dead, of the line in the pump. :( these pumps have gears, like our oil pumps. IIRC, there's a shear pin if the gear siezes. Anyway; you have a fuel pump replacement in your future.
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You mean another one. The one I'm speaking about is brand new and it doesn't pump.
 
Grog6 said:
It happens. There's a special piece of hose that get's buried in fuel; some pumps come with the wrong kind, and it dissolves.
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ITS BRAND SPANKING NEW!

Edit: Returned the pump. Didn't get a replacement. Can't afford the correct one at the moment.
 
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I just happened to find a thread on this forum about whether one should cut a flap or hole in the backseat to replace a fuel pump or to drop the tank.

I believe it was race cougar who said it takes far less time to snip a hole than to drop the tank. For some reason the thread was closed forth further replies.

I just wanted to say that with the proper tools and practice, you can drop the tank in 20 minutes. I just did it. Of course I have a lift and I have a transmission jack. In no way could it be done in that amount of time if one did not have those tools.

Also I did the same thing yesterday and then had to track down a problem so I am fairly practiced at it and everything had been broken loose the day before so...

I have done this job on the ground at least two other times, both times on the ground in the dirt with a floor jack and no Jack stands. I do not think I would ever consider doing it that way again being the old man that I am.

And just for some comedic relief, if you do decide to cut a hole underneath your back seat for access, I am enclosing a picture of one of my parts cars that had the fuel pump replaced by somebody other than me. This is definitely NOT the way to do it.
 

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OK, I've just installed a feul pump in a bone dry tank. I'm not getting fuel to the fuel rail. I've fixed some issues with fuel line that I thought were the problem, but with the fuel filter disconnected from the source end, when I turn on the key I hear the pump run for 2 seconds and quit. I cycle a few more times expecting a puddle of fuel to be on the floor but there is none.

When I put fuel in the bone dry tank, I only put in about 4 and a half gallons. Is this enough to actually bring the level up to the fuel pump pickup? I remember the last bone dry tank I filled up taking 18 gallons. Every time I fueled up afterwards when the gauge says empty I only get in about 14 gallons.

Is 4.5 gallons in a bone dry tank enough to allow the fuel pump to pimp fuel? I hate to spend $20 more to see if that is the issue but if y'all decide I might want to try, I will...
 
I've only ever done the fuel pump once, back in '99 and I don't remember it being that difficult to drop the tank. I did it in my back yard with a jack and minimal tools. At that time, I had never heard of cutting an access hatch and I never considered doing it. I have seen some hatches on here and the other site that looked pretty good, but I probably would not ever do it. The easiest part of doing the pump back then was getting the pump. I just walked into the Ford dealership and got the whole assembly, I think it was around $200.
 
GRWeldon said:
OK, I've just installed a feul pump in a bone dry tank. I'm not getting fuel to the fuel rail. I've fixed some issues with fuel line that I thought were the problem, but with the fuel filter disconnected from the source end, when I turn on the key I hear the pump run for 2 seconds and quit. I cycle a few more times expecting a puddle of fuel to be on the floor but there is none.

When I put fuel in the bone dry tank, I only put in about 4 and a half gallons. Is this enough to actually bring the level up to the fuel pump pickup? I remember the last bone dry tank I filled up taking 18 gallons. Every time I fueled up afterwards when the gauge says empty I only get in about 14 gallons.

Is 4.5 gallons in a bone dry tank enough to allow the fuel pump to pimp fuel? I hate to spend $20 more to see if that is the issue but if y'all decide I might want to try, I will...
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It should be. I've had bad out of the box pumps for my cat.
 
Ive done a dozen of them on the ground on stands in about 90 minutes. Once you understand how it's all together, it isn't hard to get undone.
 
You need to order a Walbro fuel pump, you need to be more picky about buying parts for the SC 3.8.
 
supergordo said:
Ive done a dozen of them on the ground on stands in about 90 minutes. Once you understand how it's all together, it isn't hard to get undone.
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If you say so. I've done it at least 6 times, three in the last two days! I know the process well. On the ground is no fun. If you are young, like when I first did it 20 years ago it's not ad bad. For a 60+ old guy who fell off a barn some years ago, I'll pay somebody to do it before doing another on the ground. That's just me. Not a lot of gung-ho left in my body!
 
KEVIN8989 said:
You need to order a Walbro fuel pump, you need to be more picky about buying parts for the SC 3.8.
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Thank you for telling me what I need. I need about a $40K a year increase in my pension.

Right now, I need this car to move and I don't have the budget for a double-priced pump at the moment. I appreciate your sentiment. I know the value of my one in 722 1994 5-speed SC. When I'm actually driving it and what's in it doesn't do the job, I'll be more picky. Until then I just need it to move so I don't have to push it or pull it around my lot.

As I said, I'm aware of what I have. I've had it since 2002 and I'm not about to part with it. I'm well equipped to work on these cars and know pretty much what I'm doing. Obviously if I knew EVERYTHING about all things Thunderbird related, I wouldn't be here asking questions...

And I actually have more than one I'm working on...

Just please be more careful and less condescending when you tell people what they NEED in the written form. I know you didn't mean it that way. I apologize if I was too harsh.
 

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So, I've pulled this tank out now for the third time. I'm certainly a gluten for punishment. Looking at the fuel "tray", the fuel only rises about 1/4" above the pickup point of the pump. Because I really do t want to return it and wait 2 days for a replacement, I'm going to get more fuel and give it one last shot to work.

I'm attaching a pic but it's not super clear, maybe it illustrates what I'm saying...

EDIT: is that big puddle of hard putty looking stuff supposed to being the center? I don't reme.ber if it was there in other cars I've done...
 

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GRWeldon said:
For a 60+ old guy who fell off a barn some years ago, I'll pay somebody to do it before doing another on the ground. That's just me. Not a lot of gung-ho left in my body!
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I feel the same .. 40+ and I fell off a 3 foot fuckin ladder. 🤐 I'll just pay my 2 teenage boys to do the work for me at this point.
 
I started a new pump with about 1-1.5 gallons in the tank previously. It might have been less than that. I remember going to the gas station to fill up and it stalled because the gas station was on a hill and it couldn't make it up the incline to make it all the way in. I'd say if the car is sitting level then 4.5 gallons should be more than enough.
 
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