Stealerships would scare LR owners into replacing the fuel pump around the 60K mile mark, a scare tactic making a killer profit off LR owners. It was a money maker during the free fuel tank recall replacemnt years ago charging you something like $300 to $360 for it. Bottom of work orders, "Customer Pays" big bill along with your freebie tank replacement.

Alternators, starters and distrubutors having any issue no matter how small are stealership replaced as a unit only another big dollar profit. Small parts like brushes and bearings costing very little rebuilding alternators and starters as example. Lucas starters are rubbish Bosch coming in close second. One Nippondenso starter outlasting a couple Lucas and Bosch starters combined when a D1 was used as a delivery vehicle started 40-50 times daily I serviced for a friend.
Later found a good honest starter, generator alternator rebuilder by a person 45 years in the business telling me to install a Nippondenso starter, I was six years ahead of his advice. Told Lucas and Bosch not worth the small replacement parts to rebuild them with failing pastic parts inside them.

On another note an engine that cold start fires up on the 2nd or 3rd cylinder over compression is rather easy on starters. Failed starter with a 5 spd not a problem getting started and home again.

If a dizzy engine service the mechanical advance, clean and grease (REESE teflon hitch ball lube my flavor).
Vacuum advance nipple at the throttle plate has a very small orfice delaying the vacuum signal to the vacuum advance unit. Enlarging that orifice will allow a quicker vacuum advance with a quicker throttle response. That there is a "performance improvement".especially with a 5 speed and 94 and 95 OB1 LR's.
Keep and eye on the vacuum advance unit and give the unit a vaccum leak check as they will fail, another performance improvement if wotking properly.

At 143K, 26 years service the original fuel pump is still produces 92 psi with the regulator return line pinched off. I'm not worried about a "sudden failure".
One friends 94 D1 at 183K the fuel pump started acting up not cycling before startup. Thump the gas tank a couple times the pump starts running again. Ran normal for several days even weeks.
This pump failure warning carried on over 2K miles, plenty of warning time to replace it.

Unless your pump can only producing pressures lower than the bypass of the regulator then yes a slight "performance" improvement and better overall running can be had replacing it. Higher pressure, larger lb/hr injectors within reason the ECU will shorten the duty cycle correcting for proper F/A ratio.

Regulator bypassing below spec which is near minumum spec and common even new plus single dribble Lucas 1980's design injectors are not the best combination to begin with atomizing fuel. Higher rail pressure plus 4-hole injectors resulting in smaller droplets and finer atomization for a better bang and lower emissions as these LR's are rather dirty emission wise. Being placed under STAR test only in Kalifornia vs regular and cheaper smog checks.

Fuel pump not keeping up with engine demand causing a leanout condition at full throttle in the upper rpm range which is rather low to begin with an automatic (sluggish) plus the ECU programed for the US market lean chipped, not much in performance to begin with and left over. Toss in **** Kalifornia smog compliant regulations more strict than the other 49 states.
Best part most smog stations haven't a clue what they are looking at dealing with a OB1 LR.
Making friends with a good smog person having mechanical abilities that can also speak English. My guy zips through the checkoff list and goes right to the sniff test knowing my D1 up close and personal. He has a MGBGT with a warmed over 4.6 LR engine.....~~=o&o>.......

 

Put in new injectors. Pickup is a bit better the lagging throttle response seemed to have lessened a little bit. However the long starts are still an issue. It seems as though after fuel is primed it will fire but after long sits it takes awhile. I'm still thinking weak pump or check valve.

OH and now oil light is on! Put on new oil return lines last year was fine till start up this year. After sitting 5 months. ??? I believe I checked the oil pressure when changing lines but cant remember reading. However I never ordered a new pump so must have been good nuff.

edit: ill try a new sensor/oil filter and check pressure running Rotella T4

 

you checked fuel pressure ? fuel pressure regulator ?

 

yea its 28-30. I forgot to order a pressure regulator its sitting in my cart online lol. So I decided to just put it back together lol.

However I did just test oil pressure and its 40psi doesn't drop on rev. So will order regulator and oil sensor... and possibly the fuel pump.

 

Could it be something as simple as the fuel filter?

 

I was thinking that might be as well. I changed it when I did the pump however the lines are so rounded off I had to clamp the hell out of them with vise grips to get em off. Its not wet and I don't smell any fuel so have not attempted to change it again lol. Those lines will be next I guess.

 

Say good bye to the rounded heads when you get this Purolator F67221 fuel filter

 

nice ill have to get new lines yea? can mabye get one off a donor car?

 

You may not need new lines. Just cut the ends off and use a quality clamp when attaching to the new fuel filter.

 

oh nice didnt think about that. I have an filter like that and its much longer will have to go measure. might work.