Ford Laser TX3 Fuel Pump Replacement
When working on old cars, you are often dealing with antiquated technology and significant wear. This technology may have fulfilled its purpose when new, but now after 20 to 30 years the current technology has undergone tremendous advances and far out performs the origonal equipment. Factor in the degradation of time and you have parts that are no longer suitable for their origonal purpose.
A recent project on the TX3 involved replacing the fuel pump. This task may sound simple on the surface, but due to age and previous modification it required careful consideration and creative engineering to get the job done.
The Problem
I knew something wasn’t right not too long after I had installed the new ECU. While the car had not been tuned yet, the fueling was all over the place and hard to get a consistent value. Luckily I had installed a fuel pressure sensor as part of the ECU install. This confirmed my suspicions as the pump was struggling to get to the base fuel pressure of 42 psi at idle, and would drop to 20 psi while driving. Good thing I had not tried to do any full throttle tuning.
This car is now over three decades old. The original fuel pump was replaced in the early 2000s with one from a Nissan Silvia. This was ok at the time as the modifications were modest. However given another 25 years and some time sitting with stale fuel in the tank, this upgraded pump is struggling to keep up with demand. Considering the car now has a modern ECU and I am planning on adding larger injectors, I feel the car is in need of a bit more fuel flow. I don’t plan on going crazy (gearboxes for this car are not known for their strength and are a bit hard to find now), so I only need a pump that will support the modest power increase and do so for the next 25 years.
The Solution
With this in mind I chose to install a Walbro 255 LPH pump that I bought from T. I. Performance. I chose this pump as it was easy to obtain, designed for an in tank install and able to supply fuel for well more power than I planned to have. It also gives me the option that if I do ever need more fuel flow (running E85 for example) I should be able to change this pump to a larger Walbro more easily.
As always the plan was simple: remove the old pump from the hanger, fit the new one in its place, wire it up, and reassemble. However, as with everything for a car like the TX3, not everything went to plan.
The New Problem
I removed the fuel pump hanger and the old fuel pump. I then mounted the Walbro pump in its place and found that the hanger inlet was slightly offset to the outlet of the pump. No big deal I guess, I was able to adjust the bracket so it kind of fit. I tightened everything up and fitted it back to the car. I turned on the ignition and was immediately greeted with the sound of the fuel pump running. It sounded different than I expected, but I just put it down to a performance fuel pump. I powered up the computer and checked the fuel pressure. 3 psi. What?
Irreversible Modifications
So out came the hanger again and I more closely inspected the pump outlet. It seems that the grommet inside the hanger inlet had perished and was not making a good seal on the pump outlet. No problem, I will just get a new one. Scouring the internet for hours came up with nothing. The closest I got was a grommet from an RX7 but it was prohibitivly expensive and not guaranteed to fix my problem. Why didn’t Ford (or Mazda I guess) use a hose to join these two like most manufacturers?
So after much deliberation with myself I decided the only thing I could do was to cut off the end of the hanger inlet to remove the rubber grommet mount and use a piece of hose to connect the two. This troubled me as I don’t like unnecessarily destroying parts I can no longer get. Also there was not a lot of the hanger inlet, so I had to get this right the first time. It was also closed to other components therefore careful cutting would be required.
With bated breath I broke out the hack saw and carefully started to cut into my fuel pump hanger, knowing there was no going back. It went without any complication and I now had room to install the fuel hose. This also solved the problem of the offset inlet as the hose was able to take up the difference.
Success!!
Happy with my modification I have reinstalled the hanger into the car and primed the system again waiting to see if we got the base pressure of 42 psi. It was 49 psi, hmm, close enough. I guess it is better to have too much than not enough.
Final Thoughts
Working on ,and especially modifying, older cars is never easy or straightforward. Anyone who tells you differently is lying or has someone else working on the car for them. However it is these challenges that make it fun and enjoyable.
The TX3 now happily runs with none of the problems I encountered before, and went onto the dyno for tuning with no fueling issues. Until it ran out of injector. But that is a blog for another time.