1998 LS400 Starting Issues
#1
1998 LS400 Starting Issues
Things are a bit crazy here in the UK with fuel availability, but I did manage to get a full tank of Supreme about a week ago.
Now, almost by coincidence, I have a wierd starting issue - hot or cold - where I have to have the gas pedal right to the floor for it to fire. And even this is on the second or third crank.
I only have the repair manual for the 1st Gen - which mentions a cold-start injector - so I do also wonder if that is blocked/malfunctioning in some way.
By the way, once I do get it started it runs like a top and drives as smooth as ever.
Any advice much appreciated...
Now, almost by coincidence, I have a wierd starting issue - hot or cold - where I have to have the gas pedal right to the floor for it to fire. And even this is on the second or third crank.
I only have the repair manual for the 1st Gen - which mentions a cold-start injector - so I do also wonder if that is blocked/malfunctioning in some way.
By the way, once I do get it started it runs like a top and drives as smooth as ever.
Any advice much appreciated...
#2
Things are a bit crazy here in the UK with fuel availability, but I did manage to get a full tank of Supreme about a week ago.
Now, almost by coincidence, I have a wierd starting issue - hot or cold - where I have to have the gas pedal right to the floor for it to fire. And even this is on the second or third crank.
I only have the repair manual for the 1st Gen - which mentions a cold-start injector - so I do also wonder if that is blocked/malfunctioning in some way.
By the way, once I do get it started it runs like a top and drives as smooth as ever.
Any advice much appreciated...
Now, almost by coincidence, I have a wierd starting issue - hot or cold - where I have to have the gas pedal right to the floor for it to fire. And even this is on the second or third crank.
I only have the repair manual for the 1st Gen - which mentions a cold-start injector - so I do also wonder if that is blocked/malfunctioning in some way.
By the way, once I do get it started it runs like a top and drives as smooth as ever.
Any advice much appreciated...
#3
Other than suspecting the gas quality, I'd try bypassing the fuel pump resistor. You can simply do it short-circuiting FP and +B at the DLC1 below (left upper corner and left lower corner). If this improves the problem, your fuel pump relay may not be working well.
#4
Thanks for reply.
It was fine before. Did a couple of short journeys on the new gas - totalling about 20 miles - with no problem. Then the trouble started the very next day.
It was fine before. Did a couple of short journeys on the new gas - totalling about 20 miles - with no problem. Then the trouble started the very next day.
Last edited by VolumeToo; 10-01-21 at 12:43 AM.
#5
Many thanks Yamae.
If this is the case, then I think I'd rather just try replacing the relay!
However, once started, the car runs fine - which led me to suspect the cold-start injector (if it exists on the 1998).
If this is the case, then I think I'd rather just try replacing the relay!
However, once started, the car runs fine - which led me to suspect the cold-start injector (if it exists on the 1998).
Last edited by VolumeToo; 10-01-21 at 12:42 AM.
#6
I have a question. Does your car accelerate and run very good at steep hills as it used to be?
When the fuel pump relay is not OK, the car does not start well nor the acceleration is not very good but runs good at flat roads up to 75miles/H = 120km/H or so. These are the reasons why I suspect that the fuel pump relay's contacts are not fully working OK.
The following users liked this post:
LeX2K (10-01-21)
#7
That is very helpful Yamae, thank you.
I have not noticed any reduction in performance, but then I have not really had the car beyond 40 m.p.h. since the trouble started, nor done any steep hills.
Please, where on the car do I find this relay? Also, do you have the part number to hand?
Regards,
Rich
I have not noticed any reduction in performance, but then I have not really had the car beyond 40 m.p.h. since the trouble started, nor done any steep hills.
Please, where on the car do I find this relay? Also, do you have the part number to hand?
Regards,
Rich
Trending Topics
#8
That is very helpful Yamae, thank you.
I have not noticed any reduction in performance, but then I have not really had the car beyond 40 m.p.h. since the trouble started, nor done any steep hills.
Please, where on the car do I find this relay? Also, do you have the part number to hand?
Regards,
Rich
I have not noticed any reduction in performance, but then I have not really had the car beyond 40 m.p.h. since the trouble started, nor done any steep hills.
Please, where on the car do I find this relay? Also, do you have the part number to hand?
Regards,
Rich
#9
Hi Yamae,
I pulled and tested the relay, which works just fine. (It has the part number marked on it, by the way.) Its contacts are normally-closed, thus bypassing the fuel pump resistor by default.
So I'm now wondering what other conditions are set exclusively for starting.
This is getting interesting!
I pulled and tested the relay, which works just fine. (It has the part number marked on it, by the way.) Its contacts are normally-closed, thus bypassing the fuel pump resistor by default.
So I'm now wondering what other conditions are set exclusively for starting.
This is getting interesting!
#10
Update: Having effectively reseated the relay, guess what? The symptom has cleared!
(However, there was no sign of overheating or corrosion on the pins - and the contacts measured 0.1R - the resistance of the probe leads.)
I'll order a replacement anyway, but go figure!
(However, there was no sign of overheating or corrosion on the pins - and the contacts measured 0.1R - the resistance of the probe leads.)
I'll order a replacement anyway, but go figure!
The following users liked this post:
Yamae (10-03-21)
#12
When I get a replacement relay I'll open this one up for internal inspection and report back.
Thank you once again for your help.
#13
New relay bought at a cost of £102. Outrageous price. Fitted, and guess what? The problem is back!
The old relay does have some carbonizing of the contacts, which may or may not be significant. As stated before, it measures fine (even though the contact pads appear misaligned).
In an attempt to inspect the crimping and wiring under the relay frame, I succeeded only in shearing the plastic mounting, with the nut and bolt rotating as one.
I gave up. (However I'd like to know where the fuel pump resistor is, and its value. Measuring from the relay socket, I obtained a reading of 1 Ohm; clearly this is not possible to measure in-circuit.)
Either there is still a problem in this vicinity, or it was all a coincidence and the real trouble is (1) bad fuel, or (2) a failing fuel pump.
Not a good day!
The old relay does have some carbonizing of the contacts, which may or may not be significant. As stated before, it measures fine (even though the contact pads appear misaligned).
In an attempt to inspect the crimping and wiring under the relay frame, I succeeded only in shearing the plastic mounting, with the nut and bolt rotating as one.
I gave up. (However I'd like to know where the fuel pump resistor is, and its value. Measuring from the relay socket, I obtained a reading of 1 Ohm; clearly this is not possible to measure in-circuit.)
Either there is still a problem in this vicinity, or it was all a coincidence and the real trouble is (1) bad fuel, or (2) a failing fuel pump.
Not a good day!
#14
New relay bought at a cost of £102. Outrageous price. Fitted, and guess what? The problem is back!
The old relay does have some carbonizing of the contacts, which may or may not be significant. As stated before, it measures fine (even though the contact pads appear misaligned).
In an attempt to inspect the crimping and wiring under the relay frame, I succeeded only in shearing the plastic mounting, with the nut and bolt rotating as one.
I gave up. (However I'd like to know where the fuel pump resistor is, and its value. Measuring from the relay socket, I obtained a reading of 1 Ohm; clearly this is not possible to measure in-circuit.)
Either there is still a problem in this vicinity, or it was all a coincidence and the real trouble is (1) bad fuel, or (2) a failing fuel pump.
Not a good day!
The old relay does have some carbonizing of the contacts, which may or may not be significant. As stated before, it measures fine (even though the contact pads appear misaligned).
In an attempt to inspect the crimping and wiring under the relay frame, I succeeded only in shearing the plastic mounting, with the nut and bolt rotating as one.
I gave up. (However I'd like to know where the fuel pump resistor is, and its value. Measuring from the relay socket, I obtained a reading of 1 Ohm; clearly this is not possible to measure in-circuit.)
Either there is still a problem in this vicinity, or it was all a coincidence and the real trouble is (1) bad fuel, or (2) a failing fuel pump.
Not a good day!
Fuel pump mileage?
Fuel filter mileage?
Fuether issue: ECT Sensor resistance (meaaured at various coolant temperatures)?