avhart

Thank you Paulo.

You see my problem is that real professional mechanics that would be able to repair my car properly are difficult, if not impossible, to find here so I basically have to do as much as I can myself. This forum, with folks like you (and many more), have been of the most incredible help to me in this regard.

Glad to hear you think the Bosch is also a good pick.

Thanks yet again,
Anthony

400fanboy

I think mechanics, most of them, can do the work without too much issue. But the main problem is diagnosis. I've been mis-diagnosed many many times or told things aren't an issue which are an issue.

So my solution is to do the legwork and research, ask for help from the knowledgable folks here... and then bring the results to the mechanic and tell them to do XYZ.

avhart

Yes Fanboy, you are basically right but the problem with our mechanics is they are too careless and unprofessional. There are those that can succeed with what I tell them to do but the state they would leave the trim and other associated systems is simply not worth the trouble. For example I have had a company work on my air con that managed to damage one of the cam position sensor connectors that I then had to fix myself when I got home.

heyTony

Wow, I just looked it up and Denso discontinued the UCF20 fuel pump line! I am sure you could use something drop-in, Chinese, similar in looks to the OE fuel pump (the fat zinc-coated one). Still some being sold on eBay. Brands like Quantum, Spectra or US Motor Works. GMB is a great brand that still uses the OE style pump. You should not have problems with Delphi.





What I have done for mine is I opted for a modern Walbro 255lph fuel pump (PN: GSS342). Now they are called TI Automotive. You can no longer use the rubber bushing in the housing as well as the grounding clamp and wire. But I have used a specific LS400 rubber base that comes in the kit for the Walbro pump and I just used a random stainless hose clamp to bind the grounding wire to the outside of the pump housing and the pump itself to the housing. (Pump is significantly smaller than original). You solder or crimp connect the wires to the OE wires of the fuel pump housing and put it back like normal. The fuel pressure system is the "return" type and the immediate regulator is on the fuel pump housing inside the tank itself. So you have no worries for the 255lph pumps because it just spits the extra back to the tank anyway. If you've noticed, the other modern fuel pump brands have outsourced to TI Automotive now too or have updated to the modern rotor pump design as well. Brands like AEM or Carter in particular. It brought life back to my motor with instantaneous response. If you don't mind the slightly audible buzzing/whining in the rear of the vehicle, its a great upgrade. My UCF20 is a drift build so I don't really mind the extra NVH. Just be aware of the fake Ti Automotive pumps out there- buy from legit sources only.

avhart

Hey Tony, your reply gave me a whole lot of great information. Unfortunately it came a bit too late as I have already gone and purchased a 'fat' Bosch pump. It was a toss up between that and the Delphi. I have heard of the Walbro as well but i went for the more traditional kind.

Thanks for all that good stuff you posted. I'm sure it will come in very handy for many others on the forum and for me too if (when) the Bosch fails.

400fanboy

For what it's worth, the car shouldn't be eating fuel pumps. Yamae is probably right - there is something else probably at play here. They are a reasonably rare item to ever go bad on this car. Plenty of us are running around on original 25+ year old pumps.

They're not a "known issue" with the car in the way that the lower ball joints, strut bar or power steering can be.

avhart

I also agree. The original pump worked fine until a year or so ago before seizing up and I also have to remember the majority of pumps I have bought since have been used ones probably with already defective motors. One of the only new ones I ever bought will still spin up immediately outside the car but because they are such a pain to replace I prefer to wait until I get this new Bosch and put that one in.

Can a dirty tank cause that even if there is no indication at all in the pump strainer?

400fanboy

Yamae and Paulo gave pretty good lists of potentials in their posts. I defer to their expertise.

avhart

Of course Fanboy, nobody knows that better then me BUT neither have addressed the particular question of if a dirty tank can cause the FP to fail - in the absence of any other noticeable conditions (one being a perfectly clean fp strainer).

paulo57509

If there is a lot of sediment or other debris in the fuel tank and the debris were to collect on the strainer, inhibiting flow and thus straining the pump, this might contribute to fuel pump failures due to an overheated fuel pump. When FI first started to become mainstream, it was thought that heat was the biggest cause for short fuel pump life. The story went, never let the fuel level drop under 1/4 tank in order to ensure that the pump was always submerged in fuel which would help in keeping the pump cool.

I doubt that your tank is this "dirty" unless it had been sitting for a length of time partially filled with fuel.

avhart

Now that's the kind of specific answer I was looking for. Knowing that I'm not perfect always had me wondering if there is some kind of 'special' or weird sort of gas slime monster that can clog my pump without a trace in the strainer. So now I think I'm safe with that

Thanks for being a sport and bearing with me.

Yamae

I still have some doubt on the Fuel Pump Control Module # 89570-50010 for a Celsor/LS400 manufactured between Aug 92 to Oct 94. As is posted here in Japanese with some photos, aged Fuel Pump Control Modules tend to fail among JDM Soarer Gen3. The major failing part is the electrolytic capacitor inside.
It would be safer for you to check the capacitor inside. The blue one contains the QAS liquid and it leaks out when aged. The module for a Celsior must be using a similar PWM circuit, I believe.

The Japanese page can be seen in English by the Google Translation clicking this.

avhart

Morning Yamae, thanks for that important info. Let me now give you some further background as a result of my investigations.

The pump had stopped delivering fuel normally so I was running a 12v test on it in my garage by a jumper between B+ and FP in the engine connector. After it ran like that for about 2 minutes it BLEW the 20 amp EFI fuse. That made me think that the pump had shorted out. I removed the pump but lo and behold it worked fine (apparently) on the bench! Still attached to the hanger bracket as well so it wasn't that.

I therefore had to conclude that the culprit was that same Fuel Pump Control Module you mentioned above. Does that make sense to you?

I then went ahead and ordered another module plus a new Bosch pump.The situation now is that the car is down waiting on the parts which I may get later on next week.

On your other discussion regarding testing the FP module I have attached a pic of it where you can see two things. First the PCB has a large burnt out section at the upper left and 2) it seems to be soldered at all four corners to the case making it relatively impossible to remove without knowing exactly what to do.

It seems that the FP module in the link has a different number to mine.



Thanks again.

Yamae

As long as the fuel pump control module is good, a jumper between B+ and FP only bypasses the module and there should not be any heat related problem. But in reality that caused the open 20 amp EFI fuse as well as the burnt module.

I worry that the module's output transistor was already partially dead and there was some leaking current to the ground. The transistor is a Power MOS-FET and it is organized by many small MOS-FETs as those look like this here. When the Power MOS-FET is damaged by some reason (surge, heat and etc), some of small MOS-FETs still survive and some others are dead. In this situation, the function of switching is still done partially but there's some leaking current too. The current causes the extra heat and it damages the Power MOS-FET more causing more current and the heat is accumulated.

What I suspect is that the module was partially dead already when you applied a jumper, it caused the extra heat and the damage became bigger and the fuse was blown.

If I were you, I'd try using a good working module and drive the fuel pump motor.

Judging from your burnt module, it is almost impossible to repair. You need to replace it finding a working one.

avhart

Right! That was basically the same way I was thinking but a lot more simplified. I'm very glad for your input. I have already ordered another module and I should have it by next week.

I will post my results when I get it going.....