Fuel pressure regulator 348 TB Euro

Hi all,

I've finished the engine rebuild but have chronic over-fuelling due to faulty pressure regulators. I have two on each bank Bosch 0 280 160 715 and 0 280 160 111. All defective, parts now discontinued by Bosch!

Anybody come across this with a solution ? Thanks

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Two on each bank? How are they plumbed? Anyhow, the 348 had a change of the FPR from 0 280 160 715, p/n 137960 (->10/90) to 0 280 160 731, p/n 147281 (11/90->) but I believe they have the same pressure setting. The later 0 280 160 731 has 3.0 bar stamped on it. What pressure do you have stamped on the 0 280 160 715? If it is also 3.0 bar, the you can use the 0 280 160 731 which is easily available as it is also used on Volvo 960 (B6304F), S90 and V90, Volvo p/n 1306965 and 3547653.

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Thanks for the reply. I have two different regulators for each bank the valve you can hardly see is the 160 715 and top valve at the plenum is the 160 111.

I currently have two Mondial T's in the workshop running a similar engine - one Euro and one US and neither are the same!

No pressure reference on either item.

 

That first part number you listed gives me
BOSCH 0 280 160 213
Which certainly looks identical.

Any ideas on 160 111? It's used on Porsche 911's also apparently....

Many thanks again

 

Hello

I replaced mine 0 280 160 715 with the AIRTEX/WELLS 5G1128 from rock auto, a bargain, even shipped to France!

 

Somebody's interesting "modification". The "pressure regulators" on top are not dealing with fuel pressure at all but appear to be in the air bypass line and connected to the throttle body where the idle adjuster screws should be (I believe, as I am not fully familiar with the early M2.5 348-s throttle bodies). Perhaps this is causing the problem you are having and the FPR-s are actually good. I would take the top "air regulators" out and install the idle screws, i.e. reinstate the bypass air to the factory arrangement first before going to the FPR-s.

Early Mondials (->10/90) had the same FPR as early 348-s, 0 280 160 715, p/n 137960. Later Mondials (11/90->) had 0 280 160 738 FPR-s. Eurospares are offering this "738" FPR for later 348-s as well (I guess it is similar to the 0 280 160 731.

 

Hi there,

Thanks for your comments. The air regulators as you call them - I agree it's some sort of air pressure control - I find referenced to a Testarossa and also some old 911's. I do have Idle control screws in place as you can see on this image. The vacuum pipes to the four regulators are full of fuel so they are dead in my opinion. Do you or any others out there have any images of what the system should look like if it is indeed modified?

Sorry for the amateur hour this is my first foray into Ferrari's I'm a Lotus specialist!

Thanks again
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You should have two of these plus brackets. https://www.eurospares.co.uk/parts/ferrari/348-1993-tb-ts/engine/air-intake-motronic-2-7-23647/142432

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As the 348 you are dealing with appears to be the early 2.5 Motronic, the above shown idle speed control motor will not work. According to the parts diagram, the M2.5 had additional air electric valves (No. 1 on the diagram below, p/n 124802) sitting on top of the water transfer manifold under the intake plenum. If the valves are not there, look for free wires with two-pin standard Bosch connectors hanging around the area (the mentioned idle speed control motor would have a 3-pin connector).

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Hi guys, I have exactly that arrangement on the Euro Mondial T also with me. This is worrying as I don't have the three pin Bosch connectors on either side for the idle regulator on either side so I'm presuming somebody has cut them when they fitted the additional manual regulators. The valves are present under the plenum and correctly wired. I can't believe someone would cut the loom or sell a car in this state for all the money as is the case here - the was sold and supposedly revised by a Ferrari specialist in France last year to my elderly customer, I found four degrees of play in the timing chain....

Attached is the ECU reference can you confirm this is 2.5 and not 2.7? This is turning into the job from hell!

Thanks again for taking the time to reply. Cheers, Richard
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Just looking at this again it would seem normal I don't have the additional valves as per Pangea's post as I don't have pipes going to my plenum. Attached are the 348 plenum (regulators removed) and the Mondial (the snotty engine).
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According to the Eurospares images I have a 2.7 plenum. It looks like this is a hybrid of parts
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The diagram you attached does not show the correct plenum for the 2.7 as it is for other parts so the plenum is just an indication. If you look at the plenum diagrams, you will see the difference (2.7 has a by-pass air port on the plenum). For some reason, Eurospares show the same p/n for both plenums, 2.5 and 2.7, (149505) which is obviously an error. The ECU you showed is certainly Motronic 2.5 (2.7 Euro is Bosch 0 261 200 457). Another obvious sign that it is a 2.5 is the TPS on one TB only (2.7 has on both).

Your Mondial engine picture is Mondial 2.7 thus it has idle control motors with 3-pin connectors and air ports on the plenum. So, everything is right except that you need to re-activate the idle air valves on the 2.5 348. You said that the valves are present under the plenum and "correctly wired" but you also said you cannot find the loom ends with 2-pin Bosch connectors (?). The additional air valves look like this (used on many other cars of the early 80's, all look the same outside but had various warm-up curves):

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The valve has a bimetallic coil inside which, according to the temperature, rotates a disc with a variable size opening which allows more or less by-pass air (more when cold, almost closed when hot). The electrical supply goes to an internal heater to heat the bimetallic coil during the engine warm-up phase gradually closing the valve to prevent too high idle. Once the engine has fully warmed up, the heat from it keeps the valves (and the bimetals inside) hot and almost closed and the electric heater is probably switched off when the engine reaches certain temperature.

I fiddled with this valve on my BMW 728i (E23) long time ago so I cannot remember exactly but these valves might be fully closed when the engine warms up. Just for testing, you may try with the bypass plugged on the 348. The engine will struggle and run at very low idle rpm when cold but, as it warms up, the idle speed should increase to normal, if the FPR-s and everything else is good.

 

The 2.5 348 will not have 3-pin connectors as it does not use the idle speed motors but, instead, the additional air valves with 2-pin connectors. Just to clarify, you either have the 2-pin idle air valves (2.5) or the 3-pin idle air motors (2.7).

 

The air valves seem to be hard to get. They are vintage now and, as I remember, did not last very long so the valves under the plenum on the 348 might be dead thus the mod to try to solve the problem. Here are a couple of links to sites selling the valves but for other cars: Porsche https://www.thesamba.com/vw/classifieds/detail.php?id=1123090 (expensive) and Holden https://www.upa-online.com.au/vk-6cyl-202-efi-auxiliary-air-valve (cheap). Although they may have different warm-up curves than what the 348 requires, they can probably work fine as the differences between these air valve curves are not very big. If, for example, the Holden air valve is used on the 348, the idle speed may not be perfect during the warm-up (a bit lower or a bit higher than ideal) but I don't think it would be an issue.

 

Thanks for that info Miroljub. Very interesting. Ive not looked that closely at the 2.5 system. I recognise that early air valve you've shown. Used on quite a few cars.

 

This German supplier appears to be a good source for the Additional Air valves. They state that Bosch 0 280 140 120 is for Alfa 75 and also for Ferrari (https://www.alfa-onlineshop.de/zusatzluftschieber-bosch-0280140120-alfa-75-fiat-lancia-ferrari-12836)

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They also have a couple of other Bosch numbers, ending 166 and 186: https://www.alfa-onlineshop.de/zusatzluftschieber-ventil-alfa-75-turbo-90-i-e-gtv-bosch-18412 and https://www.alfa-onlineshop.de/zusatzluftschieber-bosch-0280140186-alfa-33-ie-sprint-ie-neu-original-12835

The 0 280 140 186 is also available from a UK supplier: https://alfa-restoration.co.uk/shop/product_info.php?products_id=1147 Since it is good for a 1.7 lit. Alfa, two of these should work fine on a 2 x 1.7 lit. (348) engine.

 

Thanks again for your time. I'm going to try the two pressure regulators first - having thought about things it's probably normal to have fuel in the air valves as both my fuel regs are dead therefore flooding the system. I'll update when I've moved forwards. Cheers

 

This is to make a correction to my posts in this thread. I thought that the idle control valve shown by Richard, and a similar valve shown by Marc (#2 on Marc's pic) was in fact a fuel damper (as it looks almost identical to a Bosch fuel damper that I have) and that using it for idle control was somebody's mod.

The shown Richard's and Marc's valves are Bosch 0 280 160 111 and are actually for idle control and were factory installed on some very early 348-s, although not shown in any part diagrams. This valve was used on Porsche 911 2.7 (p/n P14960-91111022000, called "Vacuum Limiter') and Ferrari Testarossa, 308, 328 and Mondial (Ferrari p/n 115741, EXPENSIVE). So, it appears that it was installed on early 2.5 348-s either as an initial concept which was soon replaced by the 2-pin bimetallic idle control units or it was used to finish the stock left-over from the previous models. 2.7 348-s had the 3-pin idle control motor. The history in pictures:

Richard's Idle Control Valve (early 2.5 348)
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Marc's Idle Control Valve (early 2.5 348)
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2-pin Idle Control Valve, Bimetallic (2.5 348)
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3-pin Idle Control Motor (2.7 348)
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